install service pk 2 this has a pop up blocker and an active x download prompt warning. try setting up the content advisor in ie6 maybe too and disable the 'messenger service' in 'control panel/administrative tools/services'.
install spywareblaster to stop a lot of spyware even getting on in the first place click here and update it often too. this should stop a lot of pop ups etc.
install and keep any antivirus software up to date and scan often, back this up with something like adaware or spybot.
try firefox click here ps. i would still install sp2