1. Turn off the firewalls (Vista and XP) and see if the printing works then. If it does, then file and printer sharing should be enabled in both firewalls.
2. To message another computer on the network, you can either use an instant messenger such as MSN or do a Google search for some free programs (usually made in VB) that allow message pop-ups to be sent. I think there might even be a Command Prompt command that lets you send message pop-ups but I can't remember.
3. Download UltraVNC (click here) and install it on both machines. Run the server on the machine you want to view/control and run the viewer on the machine you're going to watch/control from. Type in the computer's IP address that you want to view/control (you can find this by hovering the mouse over it's blue eye icon by the clock). Also remember to set VNC passwords.