Hard drive available space question..

I'm looking at getting a new hard drive for my 360..

either a 60gb or 120 gb...

how much space is actually useable on them?

i guess its 2GB for system use

7GB is stored for system use. A 20GB will have 12-13GB available and I believe my 60GB has 53 available :) I assume it is the same for all variations.

60GB=53 available

120GB=107 available

250GB=228 available