how to check my ps3 memory

How do i check how much space i have got left on my hardrive it keeps saying not enough space left but i am sure i aint used this much? I have got a 40gb if this helps.

On the XMB, Settings, System Info.

New HDDs are fairly easy to install and not too expensive these days.

http://www.gamespot.com/features/6176090/index.html?tag=result;title;0

Thanks

Settings -> System Settings -> System Information

It should say

'Version 3.15'

'Your IP Address'

'0gb - 36gb' (or something similar)