Personal preference for me is Superantispyware as it out performs AVG at every step, plus it has some built in repair tools. Spywareblaster is a must as that passively protects parts of your registry

http://www.superantispyware.com/downloadfile.html?productid=SUPERANTISPYWAREFREE

http://www.javacoolsoftware.com/spywareblaster.html