The Turbomemory, while good in theory, doesn't work too well in practise.
I'll assume you play modern games (why else would you consider the 5792?) so I'd suggest you get the 8800m GTX if you can afford it. That way, you'll last farther into the future, or else in a year or two you might be smacking yourself because your laptop can't play the games well anymore.
Even if you play CounterStrike, the massive overkill caused by the 8800 will trickle down into your elite n00b ownage powers, unlocking the hidden "PWN N00B" ability that will be triggered whenever your mana fills up.
(I'm joking btw)