Set Default Printer for Each Network Location in Windows 7
In Windows 7, on mobile computers—laptops and netbooks—you can set default printers for each network location. This makes it much easier for end-users to print at different locations—work, remote offices, home, etc.
From the Start Menu or Control Panel, open the Devices and Printers window. Select a printer and click Manage Default Printers. Then choose the Change my default printer when I change networks option, select a network, the default printer you'd like to use, and click Add. Repeat the process for other networks.