There seems to be two products from LavaSoftUSA - Ad-Aware, which I use, is not a background process but run as and when you decide to clear out all the spyware that you have picked up on-route. Ad-Watch, which I have not tried, seems to be a memory resident product that monitors and blocks spyware immediately.I am happy with the Ad-Aware product. It runs automaticaly when I boot up and does the job for me. It does not conflict with anything else I run. I am sure that there are other good products on the market, and for some manual routines, which work equally well.
Hope this helps and gives no offense to anyone who seriously believes that their way is best;-)
Cheers
Dave the Gnome