Windows Live OneCare has been discontinued on 30.6.2009 and and has been built on RAV technology. Successor is Windows security essentials - a freeware tool. In short OneCare it is history...
I quite often use antimalware (or shortly MBAM) from Malwarebytes - a freeware version. This version does not have realtime scan, but it is quite effective against all sorts of malware.
