coming from someone in the ISP business I can tell you it eats up support time for sure. Plus I have to support all freinds and family
One of the worst was my son, who "has" been using kazza(sp) it was the worst at loading this crap on his computer. I had to ban that and just about any downloading for now.
I use Ad-aware 6.0 it's good, just have to keep it updated(daily)