a friend of mine has brought a computer that has a sex dialer on it unkown to them witch whenever they connect to the web tries to connect to a premium rate phone line how do they remove it

-Most spyware scanners would remove it (spysweeper and others)

-A good AV would most likely remove it too (like kaspsersky)

Or you could remove the registry entries and delete the files by hand and all that - but if you're asking how to, then perhaps that's not the way you want to take.

And if you got a bunch of dialers on your PC, chances are you got a lot more junk on it (spyware, trojans, backdoors and what not), and again, a good spyware scanner + AV will help with that. And my guess is - you use IE (and that's how you got infected with all that junk), so you can consider using Firefox instead... And upgrading to SP2 if you haven't done so yet (a basic firewall couldn't hurt either if you don't use one)

See here. Tech support for Adware/Spyware removal.