Two things ... first, the Hardware Forum would probably be the most "natural" fit for the question ... and second, as it takes balance and not any one part to make this run well, anyone giving an answer would need to know the rest of the specs. Putting a Lamborghini-quality v-card in a '92 Satellite laptop is a bit of expensive overkill, for example.
And off the Hardware forum the Tweaker's page has tons of data on video cards in real-life application within the Adobe DVA's.
Look for a laptop with a GeFocre GTX graphics card for real practical and higher performance characteristics Check out the Premiere Hardware forum and look for gaming category laptops. I am editing three AVCHD camera videos on this upgraded laptop (2 SSD drives) and am absolutely pleased. You really have to have it plugged in to the AC