Well, if you want the fastest raw gaming performance, then the Nvidia GeForce Go 6800 Ultra 256MB GDDR3 would be your choice.
If you want a mobile workstation environment and want the premium workstation style graphics card with optimized OpenGL support, then the Nvidia Quadro FX Go 1400 256MB GDDR3 would be your choice. Also, this card plays games just fine since it is the equivalent of the Nvidia GeForce Go 6800 256MB GDDR3 that Sager also sells on this model.
Also, if you want excellent performance, but just do not want to pay as much for the 2 cards above, you can save and get the ATI Mobility Radeon X800 256MB GDDR3 or the Nvidia GeForce Go 6800 256MB GDDR3 (Non-Ultra). These cards are pretty much equivalent in performance, with the GeForce Go 6800 still being preferred by most.
Hope this helps.