Not all software has to cost a lot to work well.  As a matter of fact, some of the best is absolutely free.  Here's a collection.
All software on this site is tried and true freeware.

Alternative Software
This section includes free applications that provide functions you need but do it using less resources than the originals.
Foxit Pdf Reader - a very nice, small, fast Pdf reader.
Quicktime Alternative - a very small and efficient way to play quicktime movies.
Real Player Alternative - ditto on Realmedia video.

Email
Microsoft Outlook and Outlook express are a part of windows and share Windows vulnerabilities and other problems.  Eudora is a very nice alternative that is free in sponsored mode.
Eudora Home Page - downloads and how to guides.  
Eudora Spam Filter - (cecilw.com) a great site explaining spam filtering in Eudora and offering free downloads of ready-made filter files.
Changing ports in Eudora

Multmedia
PowerBullet Presenter - create animated flash presentations.
Frontpage Express - free, lite version of Frontpage, but still a versatile web page builder with some advanced features.
Frontpage Express Tutorials and Forum  - good site for how to guides for Frontpage express.
K-Lite Codecs - K-Lite Codec Pack is a collection of codecs and related tools. Codecs are required to encode and decode (play) audio and video. The K-Lite Codec Pack is designed as a user-friendly solution for playing all your movie files.

Special Applications
Natural Voice Reader - a simple, free text-to speech application.

Utilities

Cleanup! 4.5.2  - is freeware and is simple and effective for removing temp files. 
Tweaknow Regcleaner (from download.com)- safely remove obsolete registry entries.
UninstallAbility - ensures that you will always be able to uninstall unnecessary or unwanted programs from your computer.
Duplicate File Finder - find redundant files easily with this little utility.
SyncBack -  a flexible, powerful backup and synchronization program that allows to to maintain backup copies of your files and folder, or to synchronize them, so that both locations always have a complete copy (e.g Laptop/PC). It offers different types of actions that let you choose how older and newer files are processed, which files should be excluded (by mask) and more. SyncBack also supports scheduled projects, FTP and zip compression of backups, as well as network login, and simulation runs.
Eraser -  a secure data removal tool, which allows you to remove sensitive data from your hard drive by overwriting it with carefully selected patterns.
CdBurnerXP Pro - a great cd/dvd burner that's absolutely free. Even creates bootable discs.

Virus/Spyware
NoHijack - removes hijacker toolbars.
AVG anti-virus - (from Author's Site) free to home users. AvgFree 8 is now available.
AVG anti-virus - from alternative Site (majorgeeks)
Spybot- Search & Destroy - an excellent free application for killing and preventing spyware.  It has a feature for browsers that will alert you when a site is trying to infect you.
Spybot Tutorial  - site for installation and operation instructions.
Spywareblaster  - spyware prevention.
Adaware  - also removes spyware; also free (for individual use only).
HijackThis! - a great utility for identifying and removing spyware; takes some thought.
Stinger - limited but effective stand alone virus scan from macafee.
CWShredder - a small, effective utility for removing Cool Web Search variants.
Zone Alarm - excellent firewall free to individuals and non-profit organizations; takes some initial learning. There are options to buy; the free one is called simply Zone Alarm
Virus/Security Page -Software & Links
Mozilla Firefox - Even the United States Computer Emergency Readiness Team (US-CERT), a division of the Department of Homeland Security, is recommending switching to an alternative browser.  Mozilla Firefox is free, easy to use, and looks good.  It will import your favorites and settings from IE, and their site has good instructions on switching. It won't do some web applications, but you can use it for browsing and keep IE for such things.

Word Processors
Jarte - a compact, free word processor and wordpad replacement. Great for older computers.
AbiWord - a free word processor similar to Microsoft Word.