I've often marveled that with Microsoft bundling so much stuff in Windows that a graphics viewer took them so long...
Here are a couple of other goodies I use frequently:
E4M (encryption for the masses) is an excellent encryption tool which which can encrypt several files into one which can then be mounted as a separate drive. Supports RC5, DES, 3DES, Blowfish, CAST, etc. Unfortunately, it looks like the makers of E4M have moved on to greener and more profitable pastures. If you can find it, it's a great prog or you can PM me and I'll send it to you. (freeware)
Cygwin is a slick program made by Red Hat which adds a unix shell (and some tools) to Windows (freeware)
Goldwave is a powerful sound editing tool. (shareware)
Another free alternative to Microsoft Office is
OpenOffice. Just as Mozilla and Netscape share the same code base, OpenOffice and Sun's StarOffice share this one. StarOffice 6.0 is just around the corner and OpenOffice is just about to release a 1.0. For those of you who used StarOffice 5.2 (yeah, it sucked) OpenOffice is vastly better. Apparently the only difference between OpenOffice and StarOffice besides price will be the exclusion of clipart.
Smoke is an incredibly cool visualization plugin for Winamp which uses fluid dynamics to create a trippy effect. Definitely a must-have.