Which macbook should I buy?

I'm a software product manager, and I made the same choice about eight months ago (the MacBooks have been updated once since then).  I chose the MacBook, and it hasn't given me a single moment of regret.  It's powerful enough to run a number of applications (Excel, Word, iTunes, Firefox--even Parallels), all without any noticeable lag in performance.  As for plusses on the Pro side, don't forget the back-lit keyboard!  ;-)

One (less trivial) difference is that the Pro features larger screens, so there's a question of how you feel about the screen-size-vs.-portability issue.