TiBook internal hard drive

[Carl Flatow]

I'm using a TiBook 400 mHz with the original 10GB hard drive. (well 
actually it's not the true original, but that's a different story.)

It seems to be time to upgrade my internal hard drive.
I would like to eventually use FCP to do some editing.
I have an 80GB 7200rpm external FW drive.

I'm told that in order to do editing with FCP one needs to use a 
7200rpm drive, and I expect that I would use that external drive.
I also understand that if I try to replace my 10GB with anything faster 
than a 4200 it will get too hot.
Ideally, I'd like to take the 10GB that I'm removing, put it in an 
enclosure and use it as a spare external.
Is it practical to buy a bigger drive that's already in such an 
enclosure and just swap them?

Also, the IBM 10GB I have is REALLY NOISY!

Any suggestions, oh wise ones?

Carl