The new Macbooks use DDR3 1066Mhz SODIMM.

Looking on websites around the place not many places stock them and if they do there $150 - $200 per 2GB module.

Apple's price to upgraded to 4GB works out quite well and there is a gurantee that the RAM will work with the macbook.

The 5400rpm SATA HDD's are perfect speed for the mac. You can always wack in a 500GB 7200rpm SATA 2.5" drive and use the 250GB and a external Backup.