I've not bothered with virus software for years and never had a virus.
IMO, get a good firewall/ADSL router (instead of connecting directly from your PC) and don't open any attachments that you're not expecting (even if they're from a friend's email address). The firewall/router will stop all the worms from reaching your PC (which are the main threat) and not opening dodgy attachments will save you from the rest.
Unless you have other PCs on your network or use floppy disks from net cafes and such, you should be safe. I've been using PCs all day for years as a programmer and never had any problems (baring one incident when an office member connected an infected laptop to the network).
Saying that, I installed the "free" (if you call 2 months only "free") copy of Norton when I got my new board recently. It started slowing my machine down, crashing and all sorts. I removed it and decided I didn't need one anyway!
Just my opinion though and feel free to be safe Oh, and no idea which virus prog to get