Most laptops can't be upgraded as the GPU is soldered in. Custom build lappies (i.e. Clevo) can be upgraded but only within families.
here's ya choices in the Clevo 370EM
http://www.lpc-digital.com/sager-np9370.html
AMD® Radeon™ HD 7970M 2GB GDDR5 - ETA April 29, 2013 $0.00
Dual NVIDIA® GeForce™ GTX 670MX's Total 6GB GDDR5 in SLI $150.00
NVIDIA® GeForce™ GTX 680M 4GB GDDR5 Memory $200.00
Dual AMD® Radeon™ HD 7970M's total 4GB GDDR5 in CrossFireX™ - ETA April 29, 2013 $350.00
Dual NVIDIA® GeForce™ GTX 680M's total 8GB GDDR5 in SLI! $850.00
NVIDIA® Quadro™ K5000M Graphics with 4GB GDDR5 Video Memory $1,800.00