NOD32, in my opinion provides the best balance between resource use and error detection rate.
I swear by it...i get a kick out of removing Norton off many machines and install NOD32 instead.
Norton is "good" only because it has a good detection rate, so is Kaspersky (best detection rate)...but Norton is a resource hog and KAV is WAY too system intrusive.
NOD32 does exactly what a virus killer is supposed to do.....good detection rate and barely notcieable that it's even there (except if it catches a virus