Well, if you had your comp running at a fairly reasonable speed, going fast for its cpu and such, and then one day its just soooo slow, then yeah, that's spyware. Yeah, just run a good spyware sweep (adaware, spybot, mircosoft antispyware...) and then even an anitvirus check (avg is free) and you should be fine. Also, don't forget to defrag your harddrive.