Windows Exchange server - help needed.. 2 instances, which do i need?

my server is running win2k pro + MS exchange 2000. I'm really short on disk space so ive been looking at things to delete to make more space.

I noticed that there are 2 instances of exchange on the disk. One in D:\ and the other in D:\program files.
The contents of these two are similar but not the same. They are both over 3GB. (there are only 10 accounts!)here is a tree diagram

Also, there is another partition G:\ which is labelled Exchange, but is only 3mb big. In here is a folder called MBX and another called Public folders.

If anyone can tell me what i can get rid of, if anything, i'd be really really grateful.

Thanks in advance,

 

The one in Program files looks like a full Exchange 2000 install but dont take my word for it