There's a pretty big chance that if you do get a laptop for high resource tasks, you might as well buy a desktop, as they are much cheaper for the performance. Or, if you're deadset about a laptop, many batteries, as the laptops with the better graphics chips in em don't have much battery life unless you completely throttle everything when you're on one.
Instead, I'd suggest a nice, small lappy. I own an HP Pavilion TX 1000, it's a 12.1" laptop with rotatable screen, 160 GB HD, 2 GB RAM, Lightscribe DVD Burner, but its graphics chip is only a NVIDIA GeForce 6150, so it's not going to run much (though it runs Half Life 2, EP1, EP2, and Guild Wars well enough). It gets three and a half hours in battery life max, and can be configured to have a touch screen too. It's pretty nice.
AMD Opteron 185 2.6 Ghz | 2 GB RAM | 8800 GTS 640MB | Vista Home Premium