i posted this thread on another site and i think it would be useful here as well.
Freeware is usually devoid of the glutton brought on by commerical apps, and is often written by an individual who saw a need for a program and wrote it themselves. Several times i've tossed a few dollars to the programmer if i liked the program. Below is my list of favorite freeware. Linux aside, everything should run on Windows 98 or later.
Linux -- The most popular alternative OS, with worldwide support and a massive library of free software. Learning curve is a bit steep for many.
OpenOffice -- Microsoft Office replacement; works very similarly. Saves to an XML-format by default, but is directly compatible with most versions of Office apps.
Winamp 2.9x -- The most widely-supported MP3 player ever -- it plays just about every format known to man. Does it even need an introduction?
Zonealarm -- a free, easy-to-use, software firewall. Essential for anyone connected to the internet.
Firebird -- Lightning-fast browser; still in beta (try
Mozilla for a more stable alternative.)
Irfanview -- The Winamp of image viewers; has some limited image editing features as well.
Spybot-S&D/
Ad-Aware -- both remove spyware/adware, SSB does a bit more and removes more than AA.
UltimateZip -- Winzip replacement; works almost exactly the same. Built-in RAR support.
Burnatonce -- Simple but effective program used to burn CDR/RWs. Works very well with BIN/CUE/ISOs and supports overburning.
Wallpaper Changer -- Supports BMP/JPG/GIF/PNG, smart resizing, and a few other nifty features. The best wallpaper changer i've ever used.
Zoom Player Standard -- Plays more formats than Windows Media Player, loads faster.
BS Player is another good alternative.
Y'z Dock/
Mobydock/
Objectdock -- PC clones of the Mac OSX dock. Mobydock and Objectdock do more, but Y'z Dock runs better on more machines. All are XP only.
X-Fonter -- Quickly preview fonts, compare them, print out sample sheets, etc. An indispensible tool for designers.
Trillian -- AIM/MSN/ICQ/Yahoo/IRC all in one client.
SharpE -- Replaces the Windows shell; good for when you want a new look for Windows. Make sure to read the docs before installing if you've never installed a shell before.
These are programs i either use frequently, or have used frequently in the past. There's a few others programs i've started using that i may add to the list if they're up to par. Please feel free to add you own, with a short synopsis of the program. If it requires anything outside of Windows 98/XP, please note it in your synopsis.