Ok ill explain:
ET 2.60 mac version is build for the old apple’s (with IBM proc, G#)(dunno all teh things about it)
The new macbookpro uses the intel core duo proc. Intel uses x86 processors, the G5 isn’t. ET 2.60 is made for the G5 proc. Now mac osx uses rosetta to emulate the G5 proc file stuff into x86 so the Intel can run it. This means that the intel proc loses speed as it needs to emulate it.
Either choise:
-Get the Macbookpro and emulate it, it will be slow.
-Get The acer, wait til tehy crack a dualboot with mac osx on it (yes they are busy with it). Then you can just play ET on windows and use Mac OSX if u want a macbook for that
-Get the Macbook and get (or wait till there is) a dualboot with windows vista beta (windows xp is not possible due EFi bios, Vista beta might be instable and slower as well)
From your post i cant make clear what you want. Maybe you want to choose the macbook as it is better for your studie (multimedia design or something). It could be that it makes no difference and u like teh macbook as it looks nice and cuz of the ipod hype. If it is the 2nd of this, go for teh acer as you never worked with mac osx i think and you cant use windows applications, a mac isnt also meant to be a game computer as well, most is released for windows. So if you like gaming, get the Acer and be happy, then get dualboot if you need macosx later, would be nice :).