To be honest with you, some spyware can be very tricky to get rid of, I have also heard that some spyware use shared programs & .dlls, so by uninstalling them can also mean screwing up other programs who share them.
Using the known good syware remover's will usually do the trick, and you'll prolly want to run them in safe mode.Now for the more tricky one's who stay behind even after it was quarentined, can remain in the registry.
Some spyware can still run in the registry, even if it was uninstalled by windows un-installer...So to nip em in the bud, you'll have to know what you'r doing in the registry.