Use CCleaner and delete any random start up entries and of course wipe all temp/junk files
Also, do a spybot search and destroy and superantispyware scan (yea both are kinda old, but it can't hurt to use several scanners to make sure all the viruses and stuff are gone)
also, go search the registry for any strange crap if you really want to wipe out any trace manually (you better back it up/not mess with windows/microsoft stuff unless your dead certain it's not supposed to be there; delete the wrong thing, you forget up everything(from personal experience)) just google up the key before deleting it to not mess anything up further or better yet avoid it altogether