I’d recommend using an anti-spy-ware app called ad-aware. Its free and works pretty well:
http://www.lavasoftusa.com/software/adaware/
Also, in the future, your can get the Google pop-up blocker from:
http://toolbar.google.com/
Short of removing the offending application from your system, you can try and disable any unwanted tool bar within internet explorer by going to View -> Toolbars and then disable (uncheck) the toolbar in question.
But, the best solution is to remove the application by uninstalling it manually and/or using ad-aware to remove it from your system.
If you go the ad-aware route, make sure you run it periodically to remove any other spy-ware type apps that might, unknowingly, install themselves on your machine.