would: Samsung Spinpoint F3 HD502HJ 500GB HDD (16MB Cache, 7200RPM, Sata II) be faster than Western Digital Caviar Blue WD6400AAKS 640GB HDD 3.5" (16MB Cache, 7200RPM, SATA 3Gb/s) ?
There would likely be no appreciable difference in performance from the user's viewpoint, any differences would be minor. Compare warranties, product reviews, and cost. Newegg.com has a good review section for products that I have found to be very reliable assessing the goodness of products.
Either drive should meet your needs. Just determine the best bargain and move out! HOOAH!!!
Spinpont drives have gotten some of the best benchmark tests, and have good ratings from users. A comprable drive would be the ED Black series. The Blue is a bit slower. COLGeek is correct that you will really only see a small difference in speeds, but I think the prices are the same so why not get the marginally better one?
IMHO, I'd go with the Spoinpoint, and that's what I picked for my next drive upgrade after doing a bit of research.