File Sharing

I’m having trouble sharing files between computers. I have a desktop running XP pro and a laptop running XP media center. I have a crossover cable connecting them. They are in the same workgroup.

When I view the workgroup I can see the other computer, however when I try to open it, I receive this message.
” is not accessible. you might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permissions.

the network path was not found.”

What am I doing wrong?