Discovery doesn't seem to be working

I have a small 2 computer system consisting of a MacBook Pro and Vista
x64.

Everything works just fine so it isn't a firewall issue or a router
issue. For some reason my Vista x64, even though Discovery is turned
on, it doesn't broadcast it's existence. I have to manually connect to
it's shares from the Mac by "Connecting to Server". The Vista PC will
not show up in the Mac Finder. But, when taking the Mac to my work
place all PCs including Vista PCs show up fine. Something is wrong with
the Vista PC on a 2 computer network, so it seems. Any ideas to make
Vista broadcast it's existence or make sure it is actually running?


--
LCarter