Western Digital hard drives sound good in theory for laptops, but they're not. I would never use one unless they fix a fatal flaw.
What flaw? The fact that the hard drive automatically goes to sleep (parks its head) after eight seconds of inactivity, and since this is hardwired into the firmware it completely dismisses what you set in your Power Options in the Windows 7 Control Panel. Why is this bad? Because if the HDD is inactive for more than eight seconds it needs to unpark its head, and that creates a very noticeable lag when launching applications or working with files because the process takes a few seconds to complete, not to mention it puts more stress on the HDD mechanics.
Unless it's simply for a storage drive where you don't care about performance I recommend you go with Seagate, Hitachi, or Samsung for laptop HDDs instead.