I've used a Pentium 3 desktop with an Nvidia force independent video card, a Celeron Compaq 2100 with Ati Radeon (shared memory) and a Compaq nx6110 with an Intel Graphics Media Accelerator 900.

Of the three, amazingly its the Compaq 2100 that has the best graphics rendering. I'm positive it's Ati Radeon graphics chip which makes all the difference. Pictures are crisp, details are abundant.

Stay away from Celeron based laptops unless all you want is just basic computing. Multi-tasking is so tedious on these laptops, they're just too darn slow, even at 2 ghz.

Having at least 512 mb of ram or even more than 512 can really help boost the speed of your laptop if video memory is shared.

Cnet has a feature on the best laptops for Photoshop, you may want to check that out.

Good luck and happy hunting.