can I get pcs to communicate across different domains

[#1]

I have just be provided with a work pc which is locked down with admin rights and is running xp pro sp2.
I have a vista machine also. I'm trying to get the two to talk to each other and wondered if it is possible to get two pcs on different domains to talk to eachother on my wireless network.
I have tried setting my own pc up on the soame domain but I've had no joy. I can ping the vista machine form the laptop.
A

[#2]

if you run ipconfig /all on both machines and the ip address is in the same range you should be able to do it. So if the visat pc has an ip of 10.0.0.2 and the other has 10.0.0.12 your ok but if the other is 194.119.131.66 then no you cant(well not simply)
Your best bet would be to setup a user on Vista with the same name and password as the work pc as this will help.
When you log on to the work pc do you logon as a local user or as a domain?
From the works pc can you get a cmd prompt if so try
net use p: \\vistas ip\c$ / password /user:usernameonvista