> drive? And do I mount (or add) the extra space to the actual C (physical > exchange drive) > or the M(virtual exchange drive) You cannot add space to the boot drive in that manner. You really should have installed your databases on the D: drive so that this would be an option. If you are running Exchange 5.5 you could just run the Exchange optimizer and it'll move the Information Store to drive D: for you (it'll obviously take quite a bit of time to copy that much data from one drive to the other). I'd assume there is a similar way to move the database in Exch2k but I haven't looked into it.