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
+1
If you are spending thousands of dollars to play a 10 year old game you are doing something wrong. They just released Quakelive for Mac, give it some time.