God damn kids and their dad's compaqs...
Windows Messenger can be disabled as Gman said. First thing advanced users do when they sit down to "fix" a bud's XP machine.
Secondly...internet popups are entirely your own fault. be more careful where you go and learn how to prevent popups froms tarting, instead of burning processor power with some lame script that auto-closes them. Clear your cookies, tempf iles, and learn to use IE6's special feature where only certain websites' cookies are acccepted (Gamespy, Fileplanet, ESF, Livejournal for me).
Thirdly: stop downloading porn from unsafe sources. If you HAVE to get it, get it from a forum where people post links, those tend to be safer.
Fourth, "I didn't dl any porno dude mad popups wat do i do"...don't even argue. You've got it, and if it's not that, it's something else you aren't supposed to have; that is the bait for stupid advertising popups.
Fifth: tell your dad to also stop downloading porn (<---BIGGEST KILLER OF COMPUTERS I have EVER SEEN).
Sixth: Uninstall AOL, Kazaa, Bonzi Buddy, Morpheus, Download Accelerators, Download Managers, 56K speed enhancers...and all your cs hacks.
And I'm spent.