You should be able to go to Start/Settings/Control Panel/Add Remove Programs - and there you should see the Gator application, and/or something called GAIN.
You can uninstall these and then run something like AdAware again.
Other things can also cause popups as well. I'd need to see the $you save popup in order to know where it came from, but if it doesn't say GAIN or Gator on it, it's not Gator.
Go to
http://doxdesk.com/parasite/ and it will also tell you what you have, and gives detailed instructions on how to remove scumware.
See if that helps any...