There are various free spyware removers such as Ad-aware, however have found that Norton Internet Security 2004 (£18 on E-bay) makes your computer invisible on the web and as a result I have no attacks by Trojan viruses and no spy ware, compared to the 2003 version which seemed to be attacked every 20 minutes or so. The most important thing is to get software that keeps up to date, which Norton does everytimeyou log on.
Interesting that NIS 2004 is an improvement? I thought it was very bandwidth and resource hungry. I have not bothered to update my NIS2003 having had Norton for some time prior to that version, because I got fed up with it causing problems on several computers.