FWIW, IMO, YMMV, and of course there are exceptions etc. - but another "truism" is that often even a laptop that's equivalent in every way to an "identical" desktop is inferior for gaming, because the BIOS is generally optimized for power conservation. This often means odd slow downs and other quirks that don't happen in the "exactly matching" desktop system.
Of course, I'd like to believe that a gaming oriented laptop is different, but...
<S>