Does my son have a preference? Yes: A 3ghz Macpro for the desk, and a 2.33ghz MBP for on the go. And that's the dilemma. I know some would recommend maybe an Imac + MB, but I'm not sure that he really needs TWO computers. My question is really what machine has the most overall utility in a college setting. This thread has helped me to appreciate the virtues and liabilities of each option.
Unless you're extremely rich (that is to say, a multi-millionaire, minumum) or your son is going to a first-rate school to do advanced design or editing work of one kind or another, there's no way in hell that he's going to need even close to that.
I've found that a laptop-desktop combination is a waste 90% of the time anyways (at least, both brand new),
If you're even considering spending that sort of money, I'd suggest that you just get him the MacBook Pro. For what you described that should be more than enough.
If he's got to have the portable-desktop combo, a MacBook and the mid-level iMac should actually cost just a little more than the MacBook Pro.
But there's no way in hell that anyone such as you described would have need for a 3 Ghz Mac Pro. I hate to rain on your kid's parade, but it sounds to me like he's playing you. I know, because it's (on a smaller-scale) what I used to do.
Adam (Circa 1997): Dad, we need a CD Burner, otherwise we could lose all of our data? Remember the time I lost that paper?
Adam (Circa 1998): We need a DVD drive
Etc, etc.