Hmm, so on the vista machine, you open network and sharing center, click view computers and devices, and it shows you the other machines on the network, yes?
if so, you click on the other machines, and then it tells you, you can't connect. On your local network, are the machines on the same domain, and sub mask ?
Domain shouldn't be a problem, its usually "workgroup" unless you've changed it, the sub mask, if its the standard basic one that most routers give you, will be;
192.168.x.x
Mine is currently 192.168.2.10->30 with my PC being 192.168.2.21
I can view all the machines from my Vista desktop, they're all variations of 192.168.2.X , but as I said before, unless they're logged in as user Edward, they cannot access my PC.
So er, back to you, Taffy, what can you do currently, and are the machines on the same sub mask.