For a gamer, it is always better to have a PC as the hardware recommended for Graphics and power is better on more heat hungry procs and etc...Secondly the battery is the limitation in terms of charge n discharge and in terms of power being optimized for battery saving.

If i am a gamer, i go for XPS 710 series from Dell it is a Hummer 1 as we call it or custom design a system with AMD proc....u save lot of money and controll the performance....

Notebook not suggested in Gaming enviorment, though the trade off is portability but faced lots of limitation on NBs.....

All the best