Ad-Aware and Search & Destory are the best bets here are the links to them (FREE)
to make sure your getting the most of them, make sure you check for updates.
As becuase as fast as they are figuring out how to get rid of the spyware, the people are making new variations just as fast. Why? Spyware guys are making huge sums of money at the expense of internet users.... and in my eyes its plain and simple... they are damaging everyones private property ie hardware...
Here are the links"
Adaware =
http://www.lavasoftusa.com/software/adaware/
Search & Destory=
http://www.safer-networking.org/en/download/index.html