We have a total of 60 AD sites, 90% of them are Win2K GC, and the rest of themare Win2003 GCs. Do we needto upgrade allGCsbe 2003 SP1 to prepare for Exchange 2007 installation? Someone had asked this question before, but the answer seem unclear.

from: http://technet.microsoft.com/en-us/library/aa996719.aspx "...You must have at least one global catalog server in every ActiveDirectorydirectory service site where you plan to install Exchange2007. This global catalog server must be running WindowsServer2003 SP1.WindowsServer2003 SP1 is required for the following reasons..."