Best things in life are free I support Freewares. I find many of them to be better than the paid version softwares! Though I secretly admire Linux, I still prefer Microsoft OS for various compatabilities' sake. So listed below are some of my favourite freewares for Windows OS.
Compression - There are lot of players. Though WinRAR is great, I would recommend IzArc because its free! Try the rightclick cascaded menus to zip/extract
Browser - Refer my previous post on Opera. It has lot of small features not even worth mentioning in the feature list, but they are very nifty. Check the "paste and go" when you paste anything in address bar.
Image Management - Irfanview is a simple and easy to use image viewer and editor. Use this only for images. Dont use plugins. Choose Gimp for better editing.
Multimedia Player - Without doubt the popular WinAMP is the choice ! Its highly customisable ! Try real alternative and Tara's plugin if you want to play 'real media' files. For editing purposes, try Audacity.
Network Utilities - Zonealarm is good firewall free for personal use. Dont try the Pro Version! Try FileZilla for FTP Client
Instant Messenger - Trillian has cool interface and can connect to variety of services. Can also try Gaim.Trillian may not work well with corporate firewall.
I cant really recommend any free Antivirus but you can try Avast.
Programmers can use Nullsoft Installer and Winmerge.
Some other freewares that you can try are Daemon Tools, PDF Creator, PuTTY, RealVNC,httrack,Lame Encoder, 2xExplorer,DVD Shrink, WordWeb and Open Office.

There are some one of its kind freewares like konfabulator, Resource Hacker, Winroll, ratDVD, DesktopSidebar, Sharewatch, nLite, Nasa WorldWind, Adobe reader speed up etc
Book mark this link so I will keep this updated !

Edit:-
Suggestion from others...
Pop peeper to notify new mails.  ¶ 9:01 AM