for windows the network is not case sensitive. As for NFS, it is usually for unix like OS, is your other machine a Linux machine? Windows uses the SMB protocol.
Where do you get the error message from?
have you try using UNC path to access the machine directly? lets say your other windows machine is pc-01, then you do from the run command (or from the address bar in windows explorer)
\\pc-01
that should display the shared folders.
Now, if you are trying to browse the network using NFS, this is another story.
First of all, make sure that file and printer sharing exception on the firewall is enabled.
Try to ping the other machine, and from the other machine to the windows XP.
If you can give more information about the network, then probably I could be a more specific