No Unpartitioned Space – Dynamic Disk

Hi All!
I’ve upgraded my exchnage server to win2k and for doing that I’ve broken the mirror on the system disk and performed the upgrade on one of them. The upgrade went great but now when I want to reestablish the mirror I need to upgrade to dynamic but I have no free and unpartitioned space available. I really do not want to risk this server in the backup/delete/upgrade/restore routine. Any clues how can I upgrade to dynamic without the risk of losing my system disk?
TIA,
Avi