I second the old fat guy. :teeth
I've tried various pop up blockers, and I must say nothing has been more successful than firefox, and then the google toolbar.
I do however, recomend you getting adaware, as well as spybot search & Destroy. Download them, Update them, and then run them. Delete everything they tell you to, and then switch to firefox. You'll be in non-popup heavin.
Also, if it's really bad, and I mean bad, you may just have to re-format. There was a point where my computer was REALLY bad. Person who used it prior to be obtaining it was one of htose people who click the "yes, install your software" before reading what it was. I ended up just reformating because it wasn't worth my time to track down the little bugger.
Extra side note: Run two hard drives. I've found that by running two drives, it makes it a lot easier to manage my stuff when I need to reformat. I just drag over all my important files, and am done w/ it. I also have all my music and movies in the secondary hard drive. Generally when your computer gets infected by popups/viruses they attack your system drive, and thats it.