To find out how much music is on your player, go to the menu on the player and scroll down. I can't remember the name of the menu, but it's something like About ... or Info or something. It will tell you how many files you have on the player and how much space they take up.
As to the 2GB formatting, I don't think it's possible. You always lose some space between the OS files and the discrepency between bits and bytes (as I remember, but please correct me if it's wrong).
I have the m250 and was wondering how you can tell how many files and how much space your using on the player?
I tried right-clicking, on the drive via Windows Explorer, but i don't see the 'properties' option where you can view diskspace, etc..
Also, i saw a post somewhere that said you can format the drive to get the full 2GB storage instead of like 1.7 or something. How do you do that?