Given that most everyone I know has had me rid their computer of spyware at some point this past year, I'd like to suggest that you read this :website: and the associated links. The page details how you can run as a non-admin user on your machine, the advantages and hindrances (I said it) of this new setting and suggests solutions to the problems you encounter.
I've set this up on my machines at work and the setup works perfect 99% of the time. When I'm in trouble, I do some research and find the solution. In case doing this gets you in hot water, I'll help you fix the issue - promise. But please use the Limited User Account feature in Windows XP and rid yourself of nasty spyware.