Which hard disk?

I've actually had a good amount of luck with the WD Scorpio drive. It does it job and it's never died on me for no reason at all. I'm sure some people may have had different experiences with Western Digital drives, but I would definitely choose this one over the Samsung.

And since you didn't mention it in your original post, make sure that the MBP you have is a unibody since the 12.5mm height clearance needed for that drive can only be had on the unibody MBPs as well as the 17" aluminum MBP.

 

The 2.5" 1 TB drives all spin @ 5200 RPM compared to the stock 250 or 320 drives in the machine which spin @ 5400 RPM. It's not a significant difference and you'll only really notice it if you're constantly reading/writing/transferring large files to the drive. If you're primarily using the drive for storage purposes, then you'll be fine and then drive speed should leave you unaffected.

Most consumers, including those who spring for the 7200 RPM drives, rarely force the drive to spin up to those higher speeds since they tend to run middle of the road applications that don't have them reading/writing/transferring large files to and fro. The only real time the speed of the drive becomes a bottle neck is if you're doing high-end photo, video or audio work.

Hope that answers your question.