On small office and home office networks, Windows XP and Windows Vista cooperate about as well as cats and dogs. But you can teach them to get along.
When you combine Windows XP and Windows Vista PCs on the same peer-to-peer network, such as you might have at home or a small office, you may run into all kinds of problems. It may be difficult for your Windows Vista PCs to find your Windows XP PCs, and vice versa.
And the Windows Vista Network Map -- which may be the best networking feature Microsoft has ever introduced into Windows -- wont work properly with XP PCs. They wont show up properly on the network map, if they even show up at all.