Mirroring folders on NT and 2000

Hi.
I have an NT 4.0 Server and a 2000 server. i have a folder on NT, and I want the same data mirrored in a folder on 2000, or viceversa. If a modify a file from that server on 2000, I need it modified on NT too.
Can I do that? How? 🙂
Thanx