The best overall spyware removal tool that I've used is a product by Webroot called SpySweeper. It is also not free but there is a thirty day, fully functional, updateable version available on their web site ( http://www.webroot.com
). Go to the 'Downloads' section and in the area under 'Try It' you will see all of the 30 day downloads available. If all you're trying to do is clean the computer up then this is definitely the way to go. You can download it, update it, run it, clean the computer up and then uninstall it (or leave it on the computer for 30 days).
A note: you can't be clever and uninstall it and then try to reinstall it again. It leaves a registry entry behind even after uninstall that will prevent you from successfully re-installing after the trial period is over.