The biggest culprits in spreading spyware are the popular peer-to-peer programs available today. Bearshare, Kazaa, Imesh, Limewire - all of these products install multiple advertising spyware applications. It's gotten so bad that I now assume all p2p programs bundle spyware unless I've tested them personally.
Quoted with permission from »www.spywareinfo.com/articles/spyware/
Writen by Mike Healan