peer to peer network with nt 4.0 and xp

I have a small network, with 1 NT 4.0 workstations, 1 Win 98 workstation and 1 Xp Pro workstations.

The windows xp pro machine is able to see all the machines, but cannot access the NT 4.0 machine. The 98 can see and access all.
The NT 4.0 cannot see the xp pro machine.

I’ve already checked the TCP/IP settings and they’re ok.

Anything else I shoud check?