The one thing that keeps me from running NX is that it won't let me connect to my session unless both the server and client run the exact same color depth. With VNC, I can connect to my 16-bit color X session at home on my 32-bit color Windows client at work. With NX, unless both desktops are running the exact same color depth, it won't connect. If there's a way around this, Google's search hasn't shown me anything.