Over the years I have discovered quite a few FREE windows programs that are so good that they can be used in place of commercial programs that would cost you a lot of dough. Here is my list of free programs and a link to the site where you can get them. By the way I am running them on Windows XP, but most if not all should run on Vista.

Office:

Open Office - Microsoft Office Replacement
WordWeb - A really great dictionary that also gives you synonyms and so much more
Adobe Acrobat Reader - Read PDF files.
Rainlendar - Nice appointment calander.

Graphics and Photo Viewers:

InfanView - View or play any graphic, movie or audio file. Tools for drawing included. Pluggins Available.
IconEd - Simple program lets you create your own Windows icons.

Internet:

Firefox Web Browser - Replacement for Internet Explorer and far superior.
Core FTP Lite - Download and Upload files on the Internet using FTP protocol.
Telescope - Multi search engine search.
Webferret - Another multi search engine search.

Email

Thunderbird - As good or better than any email client

Audio:

Balabolka - Create audio files from text and read text using audio.
Audacity - Great audio editing software.
Media Join - Joins and converts audio and/or video files.

Players:

Flv Player - Flash movie player
Quicktime - Plays video and audio.
Windows Player - Microsoft

Utilities:

Advanced Window Care - Keeps your computer running well.
DriveImage XML - a great backup program for you computer

Tools:

Comodo Time Machine - Takes image of computer and allows rollback BEFORE windows loads for great data recovery.
Atomic Clock - Keep you computer clock accurate.
Color Cop - Want to copy a color you see on a website, this will do it.
Everest Home - View everything about your computer.
FlexTk Express - A comprehensive search tool for you hard drives.
Gadwin Print Screen - I love this little screen printer and have used it for years.
Jzip - an excellent uncompress and compress program for files.
Process Explorer - Learn what is running on your computer and take action.
ReSizer - gain access to hot keys allowing screen movements among other things.
Revo Uninstaller - a better program uninstaller that gets everything.
Smart Defrag - Defragments drives better than Windows Defrager.
Update Checker - Find out what updates are available for your installed programs.
Unlocker - Unlocks programs so that they can be deleted or other activities accomplished.
Clipboard Magic - Save multiple text to clipboard and retrieve any text saved.
Free Download Manager - Best download manager available.
Total Copy - The fastest file copy program I have ever used. Gets faster with use.
Open Expert - Allows you to open all sorts of data with any program you pick.
Xplorer2 - A great file manager. Blows Windows Explorer away.

Anti-Virus:

AVG - Good anti-virus program
Google Pack - Several free programs that give you protection from spyware, and viruses. Other interesting programs are included.
Threatfire - An anti-virus program that supplements any one that you have running.
Comodo Firewall - A little complicated, but a much better firewall than the one that comes with Windows.

I use every one of the programs listed here and I can tell you that they are all incredible for free programs and many rival commercial programs. Some even surpass commercial programs while other don't even have a commercial equivalent. Just one more thing, all the programs listed here were free when I made this list, but the status of any of them could change over time. I will be adding to the list as I find new great freeware.