I used the old spybot - was good. When I went to upgrade to more recent version about 8 months ago - it was too much for old my P4 to handle without bogging down my PC.
I'm looking for another free program to use right now - preferably something that doesn't run all the time in the background - or that takes up very little of the system when it's running.
I've got a spysweeper subscription that I'm really happy with - but I'm in kindof a transient point with 3 PCs ( 2 that are users and a future build ) that I don't want to invest in a new subscription for a couple of months.