I would like to upgrade our Exchange 2000 server to Exchnage 2003. We are currently a 2000 AD Mixed Mode environment that includes one NT4 BDC. In order to upgrade to Exchange 2003, will I need to also upgrade my BDC to 2000 SP3+? There are specialized apps on the server so it cannot be upgraded. I have read some articles that say it will work while others say that all domain controllers and Global Catalog server must be 2000 SP3+. Any help on this would be appreciated.