Multiple instances of various AVs. Usually two running at the same time. I like to mix and match when I can. I encourage clients to have at least two AVs in use on their lans too. Not two per machine (I'm nuts for that) but say, all the 95's with Norton, all the 98's with Mcafee. That way, if there's a virus on the lan that one misses, odds are the other will catch it.
At the moment, I've Norton, and whatever came in on this month's magazine cover. Vcatch, I think.