Does anybody know of the whereabouts of a good tutorial for networking?

I am trying to connect an older NT4 machine to my XP home machine.

* They can ping each other.
* I have identical logins on both machines.
* I can see the XP maxhine in the NT explorer. But I can't see the NT
machine from the XP unit.
* I am running the standard XP firewall (I suspect the problem may be rooted
here)

Any ideas where to start?