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Note: If referred to this Wiki from the Microsoft Answers forum. Note that none of these downloads are specific to Dell systems; these downloads are provided by Digital River or direct from Microsoft The Non-Microsoft/Additional Recommended Software wiki has software that I recommend available from a variety of safe locations. 
Thus the files listed below may be used on any PC (that has a readable Windows Vista/7 COA) and/or a Microsoft Office 2007/2010 license. Ensure you have product keys for  both Windows and Office at hand when using these files.
If looking for a "Dell Windows Reinstallation DVD" see here.
Office 2013
Office 2013 (Photo credit: melenas1414)

Microsoft Windows

• Microsoft Windows 8 Upgrade Offer for New PCs ($15 until February 23rd 2013)
• Microsoft Windows 8 Professional Upgrade ($40 until January 31st 2013)
• Windows 8 Media Centre Pack (free until January 31st 2013)


Note: There are no free official or trusted unofficial download links for Windows XP. 
• PageDefrag (For defragging files in XP which can't normally be defragged because Windows XP is running)

Microsoft Office


 

 


Microsoft Security Essentials

Security Essentials is included as a part of Windows 8 so there is no need to install it.

Microsoft Windows Live SkyDrive

Online storage (7 GB free can purchase an additional 100 GB) highly recommended.
Add SkyDrive as a synced folder in Windows Vista, 7 or 8.
• Skype 
Instant Messaging Software for Microsoft Windows

Microsoft Mathematics

Scientific Calculator for Microsoft Windows.

Microsoft Student Programs

• Microsoft DreamSpark

 

Additional Recommended Software 

Software I like and recommend; this is not official Dell documentation. This is written by Philip Yip, Dell Community Rockstar natakuc4.

Security

I recommend Malwarebytes' Antimalware, Windows 7 Firewall Control and Microsoft Security Essentials. Although I will mention other security software, don't install everything unless you want a really slow computer. The end user will need to pick software that they like and trust.
I recommend installation of the free version of Malwarebytes' Antimalware on all systems as it is an excellent antimalware program. The free version will only run and update when prompted so is fine to run with other security software. The pro version offers real-time protection and is a one off payment for ~$25, I would recommend it. There is no expiry once purchased.
Windows 7 Firewall Control is a stringent firewall. There is a free and a plus version.

 

Productivity Software

A must have reference manager. Extremely useful for students and academics. Add your pdf files to Mendeley, it will manage them. In most cases it will extract all the information required for referencing. It will allow you to quickly search to find a paper via author, keywords, or notes you have left. A useful Word plugin allows you to insert the reference in your word document. Free online storage of papers to 0.5 GB which will automatically sync from computer to computer. If you wish more then you can select one of their plans.
• MathType
A must have for typing mathematics in Word, Excel, Visio and Powerpoint. Much better then Microsoft's native equation editor. There is a free version called MathType lite which comes along with a 30 day free trial of the full MathType. MathType lite does most purpose, for coloured equations and additional shortcuts full MathType is required.
• BKChem
Free software for drawing chemical structure. There are many superior paid packages out there but this free software is quite useful.
The standard reader for opening pdfs. Adobe Reader was getting quite buggy of late but version 11 seems better. Adobe have a suite of pdf editing products.
Another pdf reader. This is much lighter than Adobe Reader but cannot open all the secured pdfs that Adobe Reader can.
Another pdf reader. This software has a useful inbuilt OCR mechanism, if you have scanned in a document with text then you can use this software to perform OCR to make the pdf searchable.
Prints to pdf. This is useful if you want to save a receipt or something. Note the pdf prints from this printer will just be as images. There will be no OCR for printed text or bookmarks. To get OCR from a printed webpage for example, open in PDF-XChange viewer.
If using a Microsoft Office Product you are better to use save as > pdf. The file size will be lower and the pdf searchable. There is also CutePDF professional but there are other free pdf software which duplicate most of the functions of CutePDF Professional.
Equivalent to Cute PDF Writer, some slight differences e.g. merging of files but there are better software for merging files. I prefer CutePDF Writer.
• PDFill 
An assortment of free tool for merging pdf files, deleting pages, rotating and reordering pages. This company also has an editor.
Carries out a similar function to PDFill free tools.
• 7zip
Want to make a file smaller to send by email, then compress it with 7zip. In addition 7zip can open and extract .rar, .iso, .7z and .tar files. This is extremely easy to have installed.
• Peazip
Like 7zip but a different user interface, install te one you prefer out of the two. I prefer 7zip.
• StarDock (fences, ObjectDock, Start8)
Create fences on your Desktop so your icons are always aligned the way you wish and so you can group desktop icons together in a way you see fit. There is a free and a paid version. ObjectDock is a Desktop Dock, there is a free version and a paid version. Although for Dell users they should see DellDock. This is made by the same company although there are some slight differences. Start8 gives Windows 8 the Start button and classic Start Menu back for Windows 8. There is a small price tag.
Carries out the same function as Start8 but is free.
Menu to get the Start button and classic Start Menu back for Windows 8. There is a small price tag. Not tried it yet.
• ActualTools (Multiple Monitors, Windows manager)
Multiple Monitor Taskbar, there is a free (very limited version) and a paid version. It gives a taskbar for each monitor you attach to your system. You can pin items to the taskbar, you can select to have the clock and start button on each taskbar if you wish. You can also set it so the program will open in the window that has the mouse. Windows manager, highly recommended for power users. It has enabled me t be far more productive.
Autodesk products free for non-commercial use.
• GIMP 
GIMP is a useful image editing software.
• Inkscape
Drawing software.
A variety of usable portable USB software may be found here.

Remote Connection & Virtual Machines

• LogMeIn
Set up all your PCs with LogMeIn to allow you to remote control them via the web browser. There is a free and professional version. 
Use VirtualBox to install other Operating Systems as virtual machines, its useful for testing software.

Utilities/Maintenance

• Piriform (CCleaner, Defraggler, Speccy and Recuva)
The four products by Piriform. CCleaner, allows cleaning of temporary files, which can greatly improve system performance. It has an inbuilt registry cleaner, which in my case has always worked fine but you should back up the registry when using it (it will prompt you to). Defraggler defrags the files on your hard drive also increasing system performance. Speccy quickly looks at your system specifications and Recuva is for file recovery.
Pandora Recovery software.
Belarc Advisor scans your computer and generates in depth system information on a page of your web browser.
This program is an advanced uninstallation program, it is often useful if you are having issues uninstalling a program. It has a 30 day free trial which you can use if you have problems with a program. If you have problems regularly you will need to purchase the pro version.
Wanted to repartition your hard drive within Windows without performing a clean install, EaseUS partition Manager is a free utility which you can use to do this. For instructions on using this tool see here. Note the Dell DataSafe factory restore won't work after use of this tool.
Simple and easy to use tool for formatting  media cards and USB sticks. Ensure to run the tool as an administrator.
• Unlocker
Simple tool which will force deletion or movement of a file. This is useful when Windows won't let you. Although it should be noted there is usually a reason why Windows won't let you and care should be taken using this tool.
Use this utility to completely format your computer for instructions in use See Step 7a of A Clean Install of Windows.
• Eraser
Securely erase files within Windows. If there is really something you want to wipe, I would recommend to use DBAN although more work is required with DBAN as a full installation of Windows is required with DBAN.


Music and Video

• Freemake (Video Downloader, Audio Convertor, Video Convertor)
Freemake video downloader, download and convert online video files e.g. youtube files. The video convertor and audio convertor are extremely useful.
Free DVD and Video player.
• Mirillis
SplashLite HD video player, in addition there is a paid version and screen capturing software.
HD video software free trial and then paid version.
HD video software free trial and then paid version.
• Audacity 
Audacity free audio recording software.
Free text to speech software, development is discontinued.
K-Lite Codec Pack is a collection of codecs and related tools. Codecs are required to encode and/or decode (play) audio and video. The K-Lite Codec Pack is designed as a user-friendly solution for playing all your movie files.
• 3RVX
Onscreen volume meter, Dell Quickset is better but this one is quite useful for XP, Vista and 7 for systems without Dell Quickset.
Use this software to make your computer multiregional and to prevent the annoying adverts from displaying.

 



Thanks to thisisjustincase for providing the links to heidoc.net which give Office 2007, Office 2010, Windows Vista and Windows 7 in various languages. These links (on heidoc.net) were compiled by Jan Krohn. The Office 2010 starter links were compiled by CRA2YHAVOK and spiralien.
Any ideas/suggestions for improvements are always welcome. Please leave these in the comments below.
If you are experiencing any further problems, post on the correct forum (ensure that you provide basic information such as what Operating System you are trying to install or have installed e.g. Windows 7 64 bit and the model of the Dell e.g. Dell XPS 8300).
Feedback for these wikies and your overall forum experience is welcome in the Has the Forum Helped You?thread.