Aside from the obvious storage bump, there are plenty of reasons why you'd wanna upgrade your MacBook Pro's hard drive. The guys at ExtremeTech have come up with a hand-holding guide for replacing your MBP's 5,400rpm HDD for a new 7,200rpm drive, which will give you a noticeably faster MBP. There's a lot of unscrewing involved, so you'll need a Phillips-head screwdriver and a T-6 screwdriver before you begin. Like the other HDD upgrade guides we've seen, this one is worth a read, even if you're the queasy type.
Upgrade Your MacBook Pro's Hard Drive [ExtremeTech]