Can I add a 2003 Exchange server to an existing SBS 2000 domain?

I’m in the process of upgrading an existing SBS 2000 environment to 2003 Server. It would be very useful to do this over a period of time rather than jumping off all at once. For the first step I would like to leave the current SBS 2000 server in place as the DC and DHCP host and simply add a 2003 Exchange server. If it is possible to migrate the SBS 2000 Exchange data great, if not I will export to .pst files and manually move the mailboxes … we don’t have many users. I apologize for my ignorance on SBS. I haven’t worked with it much in the past and I can find little or no information about migrating it to 2003 Server. Any advice or information you can offer would be greatly appreciated.