HyjackThis is the most powerful antispyware sweep out there. It monitors all the crap going through common system weakpoints and reports it to you, so you see absolutly everything that could possibly be spyware, keep aware though, you will get alot of false positives, so don't delete anything you recognize as safe if HT is reporting it.
If you remove spyware and it is regenerating itself you very likely have a virus propogating that spyware. Download
avast, it's easily the best free antivirus out there.
Remember, always run all spyware and virus scans from safemode. Background processes have too much control over your system on a regular boot, and there's no way you can perminatly remove viruses that are written to use them if you have malicious ones running in the background.