I am a perpetual Beta tester for Onecare, and I get the newer builds before they are released to subscribers, and free annual renewable subscriptions.
OneCare is a poor AV product. It only recieves standard certification in recent AV-Comparatives testing. I removed it awhile back as it consistantly missed malware that NOD32 online scanner would catch and clean.
recent Heuristic detection is definitely improving. 3-star certification (advanced+) [May 2009], looks like Microsoft is getting its act together.