Small Business Server 2000

I have a compaq server on which i run SBS2000 and my present problem is out of diskspace for Exchange server to mount on the virtual directory due to no diskspace. Options left with me is format and rearrange the space(last resort), delete some of the files from the exsisting drive (preferable) but what can be deleted in the Exchange server directory is important. I have 2 Directories which are taking away a lot of the diskspace. Anybody knows what is the contents of MDBDATA ???

Let me know please !! Thank you in advance !!