Yep I agree. Benchmark programs reveal theory only. It is practical tasks that reveal the overall performance of a system (can any one say "megahertz myth"?).
3D games tend to give a good indication of overall system performance as they push heaps of data through memory/CPU/GPU, and to a lesser extent the HD bus.
Quake III 1.32 for OSX can be downloaded from
http://www.versiontracker.com/macosx (assuming you have the original boxed copy) and you can run the four.dm_68 timedemo test.
You need to include what resolution, texture and colour depth you use, and what detail settings you used in order to make this mean anything.
I will do this when we eventually get one here for ourselves in the store, and post the results. we may have a wait though.