Migrating Windows NT & Exchange 5.5 to Windows 2003 and Exchange 2003

I am currently running a small network of 2 servers:

PDC – NT 4 file/print server.
BDC – NT 4 with Exchange 5.5.

I want to migrate both servers to either Windows 2000 or Windows 2003 Server and migrate Exchange 5.5 mailboxes and custom public folders to either Exchange 2000 or Exchange 2003.

We will hopefully be acquiring a third server, identical to the first two, to help ease the transition.

1. Do you recommend going from NT 4 and Exchange 5.5 straight to 2003, to 2000 and then to 2003, or just to 2000?

2. Can you provide instructions or point me to a comprehensive guide (a book, a web site, a PDF, etc.) on performing this migration? I have yet to see a resource that specifically discusses moving from Exchange 5.5 on NT 4 to Exchange 2003 on Window 2003 Server.