this may help.
what it is outlining is just that you should run some sort of spyware and adware prevention program, an anti-virus program, and a firewall (NOT the windows firewall, it is just plain crap)
also use common sence, if a popup comes up and says free screensavers, it is not going to be good. if a popup comes up and says your computer is infected with spyware and viruses click here for a 5 minute clean up, dont click there, it will just give you MORE spyware and stuff (if you even had any to start with that is)