Peter,

I use spysweeper on our computers and I'm very impressed with how much better it is than both Spybot and Adaware. Spysweeper will cost you $30 but it is well worth the price.  I think you can use if for free for 14 days and then you will have to pay to continue using it.  If you decide within the first day or two to keep it you can purchase it at the discounted price of $20.  My daughter picked up a very annoying popup virus which none of the other programs would touch but Spysweeper got rid of it.

Here's a link

Good luck,

Kevin g