How do I remove this once and for all from my computer?

Try http://www.revouninstaller.com/

Removal instructions are available at bleepingcomputer.com where they also recommend Malwarebytes AntiMalware for automated removal:
http://www.bleepingcomputer.co.....us-xp-2008

In addition to this being rogue anti-spyware, I also read that it may be foistware that gets installed with another app, probably a codec pack. I would suggest that you also uninstall the "parent" app that foisted it, if there is one. Yet another reason to hate codec packs, as if I needed any.