could someone please explain to me what mass storage mode actually is.

It makes the media card in your blackberry look like a disk drive when connected to your computer. If not enabled you cannot see the contents of the card in this fashion.

would you recommend i turn it on then. Would that mean im using the media card memory instead of the phone memory

You turn it on when it's hooked up to your computer for transferring and managing files.

Example: I used desktop manager to get all my music on my memory card, mass storage mode is another way of doing so.

thakyou much appreciated your answers

Hey Noodle22

Do you know any way to save txt messages to your card???
thanks

No. You cannot save SMS to your Media Card. You can back them up to a computer, however.

set yes > for computer detect your memory card and can read write.
set no > the computer not read your memory card and you can use while connect the pc.