Is there really that much of a difference between 5400rpm and 7200rpm drives?
http://www.allmacshop.co.uk/proddet..._320Gb_Sata_150Mb_S_2_5_Lp_5400Rpm_8Mb_Cache/
That will fit a MacBook, i guess MB and MBP have the same size hard drives!
You still pay quite a bit extra for getting the latest and greatest. This one is £135 for 320GB, the Western Digital 250GB is only around £80, for the price difference you can get an external 250 GB hard disk for Time Machine backup!