Download updates & reboot into Safe Mode to scan
To get into Safe Mode you need to tap the F8 key several times as your computer is rebooting. Don't hold the key down or you'll probably get a keyboard error and have to reboot again.
Safe Mode loads only the essential drivers needed to make your computer work. This will prevent the majority of bad stuff from loading into memory so your tools will have a better chance to find and remove all the junk.
Use FireFox as your browser to block popups
Google Toolbar
If you want or need to use Internet Explorer, Google's Toolbar will block popups and give you a search box.
Disable System Restore in Windows Me/XP to ensure AdWare, Spyware, and Virus removal
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.
Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.
Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.
For more information see Antivirus Tools Cannot Clean Infected Files in the _Restore Folder," Article ID: Q263455
McAfee Security Tips
These are common sense tips and serve as an excellent reminder. Read them!