Just need to ask a couple simple things to see if they are configured correctly. I assume that you have all the computers configured to use the same workgroup name. When you use the ipconfig /all command, what IP addresses are you getting. Can you ping the other computers on the workgroup? How are all the computers connected?
Check that you have added clients to one work group or connected to same network, its better to add them to one workgroup to access them from one domain.