The simple answer is "no" -- neither in theory nor in practice is it possible to remove "all" spyware and such. In fact, windows users have been incredibly fortunate that that stuff is removable *at*all*: for sysops who run servers, the basic operating rule is that if your system gets infected the first and only thing you can do is wipe the hard drives, reload the OS from a trusted source, and start over again (hopefully with good/trusted backups).
A better to learn how to run your system securely and take advantage of all the security machinery built into the OS (Win98 and earlier users need not apply..
) [e.g., for XP, *never* run in an admin account unless you're actually doing system administration].
