Do you think that the discrepancy is really the result of the difference in system memory, or the amount of video memory?
I'm currently putting together an order for a 15-incher (my first Mac!), and am trying to decide what to spec. I'd like to keep the cost down, but I'd like to be able to do some gaming on this machine as well, so I'm willing to spend the extra cash on the 2.33GHz / 256 MB VRAM model if it makes sense. (I'll be running 2GB of memory regardless of which base configuration I choose.)
Also, has there been any determination as to whether the 160 GB drive is worth the extra money, in terms of performance? The charts at Tom's Hardware seem to be somewhat mixed, with the Hitachi doing well in most of the tests, but not so well in the "Workstation I/O" benchmark.