Now that I'm going to get a 13" MBP for school I want to pick up a portable hard drive so that I can back up my files. The problem is I don't know which one to buy. Apple has this one from G Technology http://store.apple.com/us/product/H4803VC/A/GTech_500GB_GDRIVE_Slim_Portable_USB_Drive?fnode=5f#tech-specs then there's a Western Digital. The Western Digital is also 500 MB but It's $20 more. Are there any other ones that I should look at?