I have a Hitachi 500GB 7200 rpm and there's hardly any noise. It runs perfect.
On a scale of 1-10....how noisy is the 5400 rmp on a MBP ??? How noisy is the 7200 ???
You WILL hear the 7200. If you get the Hitachi, it's not loud like empty-room loud. But if you're near it, working on it, you will hear it. Even when your fans are not running you will hear the drive spinning and accessing. The 5400 takes some effort to actually hearing it run.
IF you don't use any intensive apps, stick with a 5400.