Laptops are useless for gaming, full stop - you just can't get the graphics hardware in them.
One of my flatmates has an AthlonXP 1700 based one (well, whatever they call thier 'mobile' processor AXP equivilants) and it can run the original UT acceptably, but not much else.
For laptops generally, I hear good reports about Dell. You can check out what they offer on thier website - and buy online too, if you like.