Jesus, there's one of these threads on every forum. This will go on forever, so I'm going to close this thread. Everyone has their own opinion of which anti-virus is the best, and it's usually the one they're currently using
Just stick with an antivirus that performs well in the VirusBulletin reports:
1) Kaspersky (best detection rates, light to moderate footprint)
2) Eset NOD32 (excellent detection rates, light footprint)
3) BitDefender (never used, but always performs well in tests)
4) Trend Micro (same as above)
5) AVG or Antivir (decent protection, especially since they're free!)
I've heard the corporate edition of Norton is decent, but I just don't trust it. I'd recommend you stay away from Norton or McAfee if possible.
Also, many of these anti-virus companies offer FREE scans online. I run NOD32 on my computer, but I often run a free scan from Kaspersky and Trend Micro, just to triple check. Just go with what works best for your computer and remember to make backups of all your data OFTEN!