Is there an option to view how much HD space you have left?

Ive got the 40gig, and im pretty sure its nearly full, but there seems to be no way of viewing this. is there an option in the settings somewhere where you can view how much space youve got left?

also can you install ANY hard drive in ps3? and how do you store the old one, wouldnt it get dust on the disk and be unreadable?

cheers

Do external drives work with the PS3? Not like the little jump drives but i mean big external HDD.Stryder_18