Please let me know step by step since I'm not an IT how to find that registry. I thought this was going to be less complicated than that.
Less complicated as in you stare at it for a while and it changes? http://www.howtogeek.com/howto/windows-vista/quick-tip-change-the-registered-owner-in-windows/,
Does the google page come up soon as you start up the PC? Or is it just the default start page for I.E.?
JDFan's suggestion to re-install the OS on that PC is a good one, who knows whats on that computer from the prior owners.