move data file from xp server to win 2000 server

A network of about 6 computers access the same accounting files. The server and 4 workstations have the accounting program and operate windows xp. The 6th computer has the accounting program and operates windows 2000. The windows xp server is lethargic and practically stalls when someone accesses it. A peer said he had the same situation and moved the data file of the accounting program to the windows 2000 computer and made made the win 2000 computer the server. Can I do this by moving the data file electronically and then just mapping each other computer to that drive? What are the steps to make the win2000 computer the server?