Without the dirty sites PM whats the Net for?
Adaware is a good program but microsofts Anti-Spyware will pick up more and also has trojan protection.
The best program you can get is Zone Alarm Security Suite if your willing to pay for it but microsofts is pretty good for Freeware
Spybots, Adware and Trojans are programs that you install usualy buried in another program. Once inside your computer they set about running amok (Trojan Horse style)
Spybots and Adware monitor your internet usage and send this information back to its Mum and she sends out pop-ups according to what information she got. This is why your PC slows down because instead of just recieving info from web pages the spybot is also storing sending and then you also recieve from the Mum
Trojans are generally more nasty allow people to access your PC from their own PC to gather bank details and such.
Someting as simple as opening an email attachment can install a Trojan. So dont open emails if you dont know who they are from ( no matter how much bigger you want your penis

)
and dont keep clicking yes on the porno sites.