Migration of Distribution group to Exchange 2007

Dear,

I have configured Exchange 2007 successfully and migrated all the User Mailboxes from our previous server i.e. Exchange 2003.
Our Exchange 2003 is still working but all users Mailboxes exists in new Exchange 2007, but I am unable to move Distribution groups from Exchange 2003.
Kindly suggest any way how can i move Distribution Groups Mailboxes with all the members. Its hectic to create the the Distribution Groups again on Exchange 2007.

Regards,
Tauseef