Re: External Graphics cards for a laptop...
The H55/H57 chipsets run Intel's GMAHD (essentially a GeForce 9400). Which as OG stated, are just to pass Aero requirements. The VRAM it runs off of is system RAM. But to an extent. It's much slower, and can't provide the same results. Further, as Agent Zero said, there simply isn't enough power behind an Intel GMAHD to run a game requiring a 9600 (G94 GPU). Though the number difference is small, the GPU power difference is fairly large.
There are some USB adapters, but iirc, they feed right off of your graphics card's capabilities. Tbh, you need a better computer to play it. You can easily build a desktop to accommodate that game for about 400 USD (no OS).
RD-PC -//- i7 950 // Evga x58 SLI // 3x2 OCZ PC3-12800 // 2x Evga GTX470 // Corsair HX850 // SilverStone TJ07