Ooh!
What you need is NOD32! I have to say it's one of the best antiviruses ever. You can check out virus bulletin, but I personnaly have some reasons (probably mentioned outside anwyay)
linK:
http://www.nod32.com1) Extremely fast. The kernel is supposedly written in Assembly, meaning that where scans of a 40 GB drive in Nortan may take hours, NOD32 only takes a matter of minutes.
2) Virus definitions updating is such a snap; basically you just set up the preliminary steps, then periodically you'll receive a message that your virus definition has been updated. No manual update necesary.
3) Very advanced heuristics - surf around for that - the basic point is that it has a very good chance of detecting newly undiscovered viruses. (Remember the MSBlast worm? I got rid of that even before it was discovered, let alone make national headlines)
4) It does what it needs to do - there is no integrated firewall or any other stuff like that. NOD32 is an antivirus and ONLY an antivirus.
5) It's definetely no memory hog.
Check it out for yourself if your interested!