What would be worth an extra $500 to you?
You're getting a 200MHz increase in processor speed, an extra 40GB hard drive, and DOUBLE the video RAM (which is certainly not cheap).
You have to look at the fact that two of those three things you'll be stuck with for the life of the computer, since they're not upgradeable. You can't put a new processor in the MacBook Pro, so you'll be stuck at 2.2GHz for the life of the machine. You also cannot upgrade the video RAM, so you'll be stuck with what's in the computer for the life of the computer. Also, for the MacBook Pro, it's nearly impossible to upgrade the hard drive since you basically have to disassemble half the computer to even get at the hard drive.
My advice is to always get the best you can afford. I think you'll be perfectly happy with either model, so it all depends on whether having the best-of-the-best is more important, or saving a few bucks is important. There is no one, best answer for you -- it all depends on your lifestyle and needs. Some people need the extra speed and VRAM, some people just want to save a few bucks... which one are you?