Migrating Exchange 5.5 from SBS to W2K

Hi All,
I’ve recently been put in the sticky situation of migrating Exchange 5.5 from its current location on a SBS 4.5 server to a Win2K Server. I’ve recieved conflicting information regarding this procedure, which makes my job no less easier. Thetwo servers are on the same LAN, but on separate domains, and since SBS can be the only DC in it’s domain and the W2K Server is setup as the AD DC, there doesn’t seem to be a way to a) Establish a trust relationship between the two and b)Effectivelymigrate all users and there mailboxes across.

All responses are welcome.

Regards
Jason