Install any *nix based OS.

standard procedure (and better):
try hijackthis, post results in forum (hijackthis forum ofc).
hope that they can help you. follow their instructions.

not the best solution:
or you could just delete IE and use firefox 3.6 + "IE tab plus" add-on for windows updates.
this doesn't remove the adware but no more opening IE windows.

EDIT: yeah ... i forgot: kick your friend's a** for installing this crap. doesn't remove the malware but releases some pressure ;)

Download and run a FULL scan with Malwarebytes. After it finishes finding your malware it will remove it all. Unfortunatly it only works on malware, so to make sure you have no virus' google Panda Antivirus and do the free online scan. World of Warcraft isn't supposed to give out virus'. Are any addons installed? If so remove them before using Malwarebytes and panda as they may be the cause of your problems. If this doesn't do anything then you will have to either wipe IE from your computer after downloading google chrome or safari or firefox, or pay for better removal tools.

Edit: Any may I ask what the ads say? And which private servers?

World of Warcraft does not have any malware. You probably got it from something else you did. If WoW did have malware, I'm sure they would have a thousand lawsuits on their hands already. I'm guessing you want to stick with Windows so,

Get rid of Internet Explorer. Use Chrome(ium) or Firefox (or Minefield). Opera is an option too. These browsers are way more secure (and faster, and generally better.)

Get rid of Norton. It has gotten better in the last couple years, but it still has terrible detection rates. See this antivirus guide I made - READ IT COMPLETELY. I would recommend Microsoft Security Essentials for you as it has high detection rates.
YOU SHOULD NEVER PAY FOR AN ANTIVIRUS.
http://img832.imageshack.us/img832/8262/antivirus24.png

Now, to fix your problem, run a full scan with Malwarebytes Anti-Malware. If that doesn't work, boot up into safe mode and run a full scan with Malwarebytes. If that doesn't work, download the Avira AntiVir Rescue Disk and make it bootable onto a flash drive. Change your BIOS to boot from your flash drive. That way, when you start up, a GNU/Linux with Avira AntiVir comes up so you can clean your files while not even in Windows. Usually this will get it. If all else fails, try Combofix.

use linux.
wow under wine:
http://appdb.winehq.org/objectManager.php?sClass=version&iId=17421

That antivirus pic link has a lie in it. McAfee Detects a hell of a lot more than Norton. I have both and McAfee seems to detect 15 more virus' a week than Norton. Anyways if the ads are human verification ads then your computer has a virus from facebook. If its the human verification its a quick simple fix. Search for 444446636-jpg-www.facebook.com on your computer if its there delete it if not go into internet explorer, Tools, Internet Options,Advanced, Reset... that should do if its the human verification ad. If not do what bchandark said.

pilojo
Those statistics are based off thousands of pieces of malware. It was tested by an independent company and those are the results. Anyway, it could be possible that McAfee has higher privileges and that's why it's detecting them first before Norton does. And having two antiviruses running at one time can cause system crashes, file deletion, instability, etc etc.

By the way, how are you getting 15 viruses a week?