When did Trend Micro all of a sudden get good? It's always been a resource hog for me.
In order of preference: ESET NOD 32, Kaspersky, Norton Internet Security
In order of cost (cheapest to most expensive): Norton IS (usually free after rebate), Kaspersky (free - $5 after rebate), NOD 32 (rarely on sale).
ESET seems to be lightest on resoures, then Norton, then Kaspersky. All of which for me have been better than Trend Micro, McAfee, Panda.
I definitely do not recommend AVG. I've always had way too many problems with it. Avast is a better free alternative, as is Microsoft Security Essentials.