Migration of ADS and Echange 2000 server

Dear all,

My current environment is 3 DC with Windows 2000 server and one AD integrated exchange 2000 server.

My requirement is inplce upgradation of root DC (from 2000 to 2003) and exchange 2000 server(in exchange server both DC and exchange need to upgrade to 2003).

I know how to upgarde the exchange 2000 server to 2003 and from microst i come to know , we ned to do the exchange migration do first.(please rectify if i am wrong)

But i have some fear for upgarding the DC.

Could you please help me to upgrade the AD in root server and exchange server. is it possible inplace migration?

Regards,
Johnson