Put in a western digital scorpio black. Easy to install (if you've got some good small screwdrivers and a torx set) in less than five minutes.
Formatted the HD using my install disks.
Could not tell any difference in noise, vibration, heat, etc. COULD tell a difference in bootup and application launch times.
Would suggest buying drive through brick and mortar store instead of online. Yeah, you'll pay more, but if you've got a loud or shaky drive you can get it replaced immedatiely rather than waiting a week.