On the plus side, since they don't actually ship the MacBook pros until the end of this month for most customers, it's very likely that by the time you get it there will be a software update that fixes this (assuming it's a video card driver problem).
Considering that software reinstalls don't help the matter and that apparently using an external display eliminates the issue so it's probably not a fault of the hardware itself, it's very likely that this is a driver issue. So ven if you get unlucky, chances are an Apple software update is in the works to fix the drivers for the video card. But your folly is still inexcusable, being a veteran Apple customer. This is the kind of mistake I'd expect from a nub.
Then again, you DID have the lack of sense to get a G4 Cube of all things, so maybe I overestimated you.