Exchange Server Maintenance..

I have an Exchange 5.5 server running on a WinNT 4.0 server. The C:\ drive is constantly running low on space, despite my efforts to relieve the problem (running Exchange Optimizer, etc.). I noticed that several folders have hundreds of MB of data, and I want to know if I can safely delete or move these files. Specifically, they are C:\exchsrvr\imcdata\in\archive and C:\exchsrvr\imcdata\log. I would like to move these to the E:\ drive if possible, but cannot risk any damage as this is a production server.

Thanks much,
Kurt G.