New Server New Tree

I have 3 small servers with one tree name. We are buying a large server and want to move the users from the 3 servers to the one big server and rename the tree. Any ideas on the best way to approach this. I have about 300 users and no applications are served. Running 5.1 sp2 now. I was thinking of building the new server into its own tree name on the same network, then moving users to the new tree. What’s the best way?
Thanks in advance…