Yeah, another vote for Nod32. Use it on all 5 computers in the house, with the workstation ones actually being legal. It's the only AV that's written in assembly, not any other higher level language, which dramatically reduces resource consumption. It also keeps an eye out for spyware and trojans. The updates are automagic, fast and numerous. I get about 2-3 pop ups a day (and that's the time that I'm actually at the pc), so the ESET team is constantly on the look out for new threats and ways to combat them. WELL worth the money.
I generally agree about NOD32 being a good antivirus program, however I think this is where it fails miserably - spyware and trojans.
I've been using NOD32 for 2 years now and it has killed all viruses that are actual files.
Three months ago I discovered I had some spyware and trojans on my pc, so I installed Spyware Doctor - it killed them all. NOD32 didn't even find them.
I've got ESET Smart security on my home PC a combination antivirus & firewall, bought and paid for, well worth it in my opinion.
You can also go the freeware route with AVG or Avast, both are good, I installed AVG on the last 3 PCs I dealt with for friends & Family.
Don't forget the firewall too, ESET SS has it built in. But you can also go the freeware route with Zonealarm or Kerio (now Sunbelt kerio personal firewall), Personally I go for the latter, it has less issues.