Question for the networking experts
 

I just added a Windows 7 machine to my network of Vista and XP64 systems.

I was impressed at how easily Windows 7 found the network -- almost Mac-like. But, it's presence has knocked the other machines off the network.

The Vista machine(which is the main server) is OK. The two XP64 computers can't see the network, unless I shut down the Windows7 computer. WTF?