Quake Live on the Mac is currently unplayable. I'm getting ~60 FPS on my 2.53GHz/4GB/13", and you can't bind mouse2 so no jumping. Playing in Windows is silky smooth, except the laptop gets too hot without smcfancontrol or coolbook
Whether or not you can play Quake depends on if it's a Windows version or Mac version. I just bought my first Mac. I got the Macbook 15" with the integrated 9400m gpu and the 9600m discrete gpu. The 9400 is definitely enough to run it and for the older quakes, run very well. I can run World of Warcraft on medium settings without any issues, even in battlegrounds, which takes more power than Quake. If you need to, you can run Windows to play games in, which I did as well. Mac does a great job even if you want to run Windows on it. I downloaded the Win 7 RC and it works great...will work through next year for free as well. So there's an easy solution if you have probs with the game....or you can install Win XP on it. Anyways, it definitely has the power to run this stuff though I would suggest making sure you have 4 gigs of ram....not sure if it comes with that or not.
I don't know what that guy is doing but quake live is not that graphics intensive and shouldn't cause the computer to heat up much at all. I would take what he said with a brick of salt because if he thinks 60fps is unplayable, he is in some other little dreamland.