Make sure you get a laptop that you can change or upgrade your GPU.
Most of the laptops out there you will not be able to upgrade or even change it out. Just a 580m card is around $400.00 to $600.00 depending where you get it and those are the 1 GB of Vram.
I know the Alien wear laptops you can upgrade or chang out. This is just food for thought. Good luck to you.
There may be a possibility that an entry level GPU for laptop such as 520M which is really bad, does have 2GB of memory, so That's not good enough I believe. So what you need to tell me is what model is actually the GPU?