I have no experience with NT Servers and this is a method I have heard about for *nix Servers. The person who used it said it worked beautifully. I will know in a week because I will be doing about 7 domains myself.
telnet into old server and from the root directory:
tar --create --verbose --file=pickaname.tar directoryname
To move to the other server:
It will transfer the file and give you all kinds of useful info to boot.
Now telnet into the new server and:
tar --extract --verbose --file=pickaname.tar
The verbose isn't really needed, it just gives you a warm fuzzy that the operation is taking place.