I just got the 2.53 with the 7200 drive and love it.
Its surprisingly quiet... I mean I can hardly ever hear the thing spin. I pretty much have to put my ear to the drive to hear it.
the 2.53 vs the 2.8...
If that <300mhz is easily going to make you an extra $300 (faster rendering) then get it... If your not in the business where having something done a little faster will earn you a larger paycheck, then don't worry about it.
I had the same thoughts and went for the 2.53. I have never had issues with speed (especially with graphics.. WOW!!!)
Just my 0.02