I went to a Symantec presentation today to learn about their new End Point Protection and to take a sip of their Kool-Aid.
They took great pains to make sure that the audience was aware that they do not sell anti-virus software anymore - they sell "end point protection". Which, really, is anti-virus with other stuff.
The point is that even according to Symantec's reports viruses are dying out. (By virus I mean a program that self replicates - not a trojan, spyware, rootkit or worm). Trojans and worms and rootkits are becoming easier to modify and deploy and signature lists (against which these uglies are compared and blocked) are becoming too slow.
The moral of the story - viruses are (pretty much) dead... they have been replaced with new threats. Symantec painted a picture of their protection product as the silver bullet that will protect a PC against all the new threats. It looks good but I'm not 100% sold. I'd recommend the product but I'd back it up with a lot of other Information Security goodies.