It is the best "affordable" gaming notebook I know.
Look also to the Toshiba P-100 or P-105 with the nVIDIA GeForce Go 7900 GS.
Sure, you'll get better gaming performances on a desktop computer and I don't recommend 17" laptops ( heavy, not very easy to carry... you lose the mobility of a laptop ).
The memory and the core clock of a mobile GPU are downclocked to save power and avoid overheating while a deskop board is clocked normally. That's why you'll get better performances with a desktop.
A desktop GPU can be overclocked, while in a laptop, is it strongly not recommended. You can also overclock the CPU in a desktop, a thing you can't do in a laptop.
BUT : with a laptop, you can carry it ( well ... do not forget that you have a 17" ... about 15 lbs with the charger ... )
Good luck !
I was looking for the best gaming laptop.
max price: 3600