Foxit Acrobat Reader - A free reader for the most useful cross-browser  document format in the world - better, faster and smaller that the bloated Adobe Acrobat.  A must for Internet browsing
AVG - One of the best free anti-virus programs available.  Anti-virus is essential for Internet use today, and this one fits anyone's budget.
Firefox - Best free browser.  IE is full of security holes - switch to Firefox
Flash Player - one of two players from Macromedia that is used frequently on the Internet.  The other player os Shockwave.  If you use graphic's or gaming sites you will eventually need these.
Irfan View - The best free graphics viewer on the planet.  In the latest version, watch for an install of the Google toolbar which you may not want
Java - Very necessary component, especially for e-commerce
Maxthon - One of the best IE replacements.  Previously called MyIE2, this program uses the IE core-code to render pages like IE, but adds many nice features, including tabbed browsing.
Real Player - A audio and video player that is being used a lot for lengthy streaming audio, such as archived radio programs.  Be careful about be talked into a paid upgrade.  It will involve a monthly bill.
Shockwave - The other, but less popular reader from Macromedia.  Shockwave is used in a lot of animated games online
VLC - This has to be the best video/audio player there is. Not because it is good looking, but because it plays everything imaginable.
7-Zip - Very capable zipper and unzipper that does not nag you to purchase like Winzip does
PDF creator from Primo. PDF creator becomes installed like a printer

File Recovery

Free Undelete - Hard Drive only
Recuva - Hard Drive and Flash Memory
Undelete Plus - Hard Drive and Flash Memory
PC Inspector - Hard Drive and Flash Memory
Zero Assumption - Flash Memory Only

Spyware/Malware Programs

Malwarebyte's Anti-Malware - Excellent tool to remove the fake security notices without going into Safe Mode. Free version is a run-time version. Paid version is real-time.
BHODemon - Think of BHODemon as a guardian for your Internet Explorer browser: it protects you from unknown Browser Helper Objects (BHO's), by letting you enable/disable them individually.  It also monitors your Registry and alerts you when a BHO is installed.  Best of all, BHODemon knows about the most common BHO's - the good ones, and the not-so-good ones!
CWShredder - Trend Micro™ CWShredder™ Version 2.15 is the latest defense against the new Cool Web Search variants.
SmitFraud - SmitFraudFix is a tool that S!Ri created to remove rogue anti-spyware applications that utilize Trojans to issue fake task bar security alerts or that change your background in order to scare you into purchasing the full commercial version of their software.
ewido - ewido anti-spyware Free is a free anti-spyware protection tool developed by GRISOFT for home use.
HijackThis - Program to analyze your PC and report what it thinks is spyware/malware.  Leaves it up to you what to do about the results, so this can be a dangerous but very nice uber-geek tool.
Spybot S & D - One of two pretty good free anti-spyware programs, the other one being AdAware.
AdAware - One of what used to be two pretty good free anti-spyware programs; the other one being Spybot. Both of these programs are falling behind from decreasing support and updates. Still have a limited amount of usefulness.

System Information

Windirstat is our favorite free tool for showing what files are consuming teh most room on a hard drive. Another useful tool is SequoiaView. File Size Tools
SIW - System Information for Windows is not only about the most complete system info program available, it is also free.