Looking good, but I'd probably avoid it for now unless I REALLY had to game on a laptop. First the battery life is terrible. It's not really a accurate comparison because it's a different CPU, but the ATI 7500 machine lasts 30% longer. OTOH, the other ATI P4 machine last significantly longer too. Second, I have been less than impressed by the (Dell 8100) Geforce2Go drivers. They can be a pain to configure properly if you're using external monitors. Hopefully the Geforce4Go drivers are better.
Mind you, I'm running an iBook with a lowly ATI Rage 128 Pro. Fine for me since I don't game much (esp. on a laptop) anyway.