Sometimes Vista and XP don't play nice over the network. The biggest
effect I've seen is a slowdown compared to networking XP to XP or Vista
to Vista. Maybe it has an effect on network frameserving, too.
I share files with the Vista laptop. They start to transfer frames in this case, but the transfer stops if I try to do something else on the desktop. I'm trying to connect to my own desktop, as well, to use it to render. But it won't transfer frames to itself, even though it says that it's connected to the local host.
Even CS4 does not have render farm capability.
Apart from 64 bit in CS5, that would be my next priority, render farm capability and some basic network support.