I'll be honest the Mx17 is sexy even though it's 2'' thick its very sexy But I couldn't get used to a numb pad on it as they most likely might have to squash a key or 2. But the battery would be pored and that on your lap would be a bad experience. I would choose the Mx17 if it as it is very powerful but I would find it useless to go into star bucks and find there's a plug no where near you and you were about to load up a video game like crysis I would be like damn. but I chose other:
MacBook Pro 17'' 2.5GHz - You may say it's not a gaming laptop but it does my gaming needs. So it may have to run crysis in medium but it has a better balance in my believe of battery between graphics and the OS X has a better chance to boot up and work than what vista on my desktop would and has the power I need as well as a DVI compared to comp.
Reasons why I would choose MX17:
The Specs are

I wanna do it.
The fans blow up at you which is cool if your into a game and about too sweat and your online.
Classy
Reasons why I choose MacBook Pro:
Has a firewire 800 and 400 so I don't have to worry about having 1 extra bay when I can set up 2 bays. Maybe a fire wire 800 connected to a HDD and a 400 connected to a dvd drive if I played games on the internal and music off the firewire.
Better Battery between gaming even if you have to switch a thing or two to medium or off.
Nice and classy.
Sudden motion censor so I wont have to buy a keng lock and just use iAlertU .
Use SMC Fan Control to speed up the fans to 6000RPM and stick it on your lap when your playing the hardest games.
I don't get to play video games much and it will be become my buddy in school which means it always has to be able to boot up in 10secs and get in there.
How ever the Mx17 would be my next purchase if apple went missing off the face of the earth. It's so specs omg I get orgasim from it.
You can upgrade the video card by yourself and it will NOT void your warranty. However, damage caused by you updating the video card WILL. Sager is really good in letting you open up the case and upgrade while still be covered under warranty.
but where do you buy the GPUS?