inet has been hijacked + kazaa spyware

hi
my inet has been hijacked by this website http://letsroll911.org/ipw-web/bulletin/bb/viewtopic.php?t=3. i never put this as my homepage. even when click on use blank and close the browser it comes back. how can i stop this?
secondly, on my local disk, different p2p network come from nowhere. i delete all of them except 1 because it won’t delete, but they just keep on coming back, plz help
last, i have 512kb broadband, but some site take ages to open up, on a dial up it will open quciker, plz can u help?
thanks