I remmember one that played music on your pc's floppy drive!
That wasn't a virus, that was a legitimate exe! But don't do it on the A1200 drives, they can't hack it.
I use 4 things, Windows firewall, Avast, Adaware, and regular visits to MS Update, this seems to keep things away.
Much the same here, except I've switched to MS Antispyware, the realtime protection is nice (and free) and it picks up more of CoolWebSearch than AdAware. Still not all of it, but more nonetheless.