Registry - need to find and replace

Just cloned an ailing drive for a customer. The new drive works fine - no problem.

Just one small issue: My customer had originally bought his PC second-hand and he'd like to remove all traces of the previous owner's name from the new hard drive.

My question: Is there a registry app that makes a simple job of finding and replacing all registry instances of say, George, with Harold?

Obviously, I can do this manually, and have done in the past. But it was a tedious job. If such an app exists as I've described above, I'd like to know about it :--))

Thanks in anticipation....

PS - It would be helpful if you're able to suggest something that you KNOW works, rather than an app that you haven't personally tried. I say this because there are several progs such as 'New Owner' which purport to change the owner's name, but in actuality only change a few instances of the entry instead of ALL.