Ok I have a problem

I check my system constently for spyware, because of a few months ago I lost all my data from a peace of spyware that slowed my system to a crawl and made it Realy unstable...
I tryed using the Recovery concole and nothing. Well my ultimet result was having to reinstall the system (no Net) and then install SP2 in safe mode then startup (with net ) and install relivent updates....
Well as a result I check for spyware now so often.
However I seem to be missing somthing here.... What am I paying for???
why am I paying for a peace of software and still has addware and spyware in it.....