I agree with the others, as depending on your use, you'll rarely need anything with 2GB's of VRAM. As mentioned, the GTX 480m has 2GB, but it will cost you a lot of money to find a laptop with the chip in it. The Radeon 5870m only has 1GB of VRAM, but it is a high performance chip as well and will cost you plenty.
What is your planned use for the laptop?