For me, I always install the following on fresh machines:

- Firefox for surfing, with adblock plus/all-in-one gestures/flagfox/firebug add-ons
- CCCP for videos
- VNC and Putty for remote controlling other machines
- 7-zip for archive stuff, threw winrar away ever since I found this app

No, I do not consider anti-virus/malware etc. a necessity on machines solely for my use, when behind a firewall (or multiple), even the default Windows one, and no urge to run anything slightly dodgy from the internet is more than sufficient Maybe for others or on higher risk machines though