Direct peer to peer problems

I'm staying over with my brother for a week and we want to hook our computers up to play som warcraft 3 vs. the computer. We have a crossover cable and ethernet cards, and successfully connected the two WinXP computers directly. The connection worked, but nothing else does. I can see him on our workgroup, but cannot acces his computer. He can't see the workgroup, and cannot access my computer directly through the address bar (I have set it up so he should be able to connect after entering a username/password and it works on other networks). I can detect his IP address, but I cannot track him or message him. And we can't play our game. After I exhausted my ideas (which was pretty quick) we ran the network setup wizard on both computers for a network without internet access. The situation did not change. Is there any step we forgot to take to make these 2 computers communicate?

 

1. Use EXACTLY the same username an password "EXACTLY" on both computers.

2. Make sure the Workgroup is EXACTLy the same.

3. Make sure computers are in same subnet. Like 192.168.1.10 on one and 192.168.1.11 on the other.

Mike