I am currently using a centrino system (acer travelmate 800LCi), and have had no problems gaming. It's got a Pentium M 1.3 Ghz, and the 64mg Radeon 9000, and it handles real well for NWN and RTCW:ET (The only games I have loaded right now). You will have to pay a premium for the Banias (Pentium M) CPU, which Intel charges an arm and a leg for, but keep in mind that the Banias CPU do a lot more work/cycle than any other processor out there. My 1.3ghz M hits like a 2.0ghz P4-m, and the 1.6ghz performs like a 2.4 P4-m (approximately). There are faster M models coming out, but you can get incredible deals on the last generation right now since they are gearing up for the new models (I got mine for $1500 after rebates, including a three year warranty, too sweet a deal to pass up!). Since we are a two computer household, it was an ideal solution for me with the amazing battery life, etc., even though the graphic card is not the greatest, since I was more concerned with mobility than supreme performance for this laptop. I get 5 hours of battery life doing normal office apps, etc., and somewhere between 2-2.5 hours gaming! Yes, i could have waited and got one with a better card and faster proc., but I also would have paid at least $1000 more (and had no laptop in the meantime). Once the M-10 card comes out, my desktop will be sold and I'll get a 88xx or 56xx Sager with its almost negligible battery life but supreme performance, and then I'll have the best of both worlds.
One final note - If gaming AND battery life are important, keep in mind that as CPU speed rises, battery life during gaming drops very quickly, but performance gains are minimal. If your going to be plugged in all the time, get the fastest proc you can, but if you want to be mobile save few bucks and get a slightly slower proc. IMHO