NT4 Domain Upgrade to 2003 (Finally)

I have just started a new role, everything that is in place has been here a while!!! There is a PDC in the northern office and a BDC in the southern office both of these are very old machines running NT4!!!
The person I have taken over from has installed an up to date 2003 server with 3 blades, the main server is a to be a new file server however only 50% of the data has been moved across!!! I want to make this file server the PDC and install active directory, however I have been told that there is loads that needs to be done for me to do this!!! This is the first time I have attempted this kind of upgrade has any one got any help for me please!!!