You might also want to use Spybot Search and Destroy and Hijack This, both free although Spybot does ask for a donation.
Hijack This is a bit different in that it will give you a log of everything running and loaded on your machine. You can then elect to have it delete any questionable items. There is a tutorial site that you will want to go to before you do anything. You don't want to delete anything that should be there. There is also a website with a message board like this where people can post their log and the experts will get back to you about your problems.
Not all anti-spy software will get everything so it is a good idea to use a few. I had serious problems with my machine locking up and hanging when I shut down. It was because of all that spyware in there.
All of those problems have been solved bit I still have a problem with search engines and some other sites notably anti-spyware sites. Everything is fine after I boot the machine for from minutes to all day. At some point I will not be able to access Google or any other search engine as well as the sites I mentioned. If I shut down and reboot everything will be fine for another period of time. This doesn't fit the usual method of operation for spyware which denies service to search engines all the time. This is easy to find. Whatever this is none of the anti-spy or anti- virus software will find it. It's real clever but someday when I have the time I'll find it. These bums should be thrown in jail!
