Ok, for XP the combination of AdAware, SpyBot S&D, and MS AntiSpyware are the best...
you may also want to install EWIDO (Anti Trojan) which has saved me many times before...
www.ewido.net, they have a freeware version with a Full Trial Version... ergo it just turns off the Fullware functionality when the Trial has expired but will continue to work in Manual Mode...
Viruses, Worms, Trojans, Spyware etc. are all Malware... but the AntiVirus Progies (most) will only kill Viruses and Worms, some Trojans, but NO SPYWARE... that is why you should always have at least TWO anti spyware progs running, ie. SpyBot and AdAware...
good luck...
