Easiest way is to buy a wireless printer so it can be used from any PC or laptop that's connected to the same router as the printer, regardless of whether any other PC is switched on or off.
To use your existing printer you need to set up a file & printer sharing network as explained here:
Share Your Printer Over a Home Network Using Windows XP
File and Printer Sharing in Windows Vista
It will mean you can use your existing printer, but the disadvantage is that whichever PC the printer is connected to, that PC must be switched on & running for any other PC to be able to use that printer.
To use your existing printer you need to set up a file & printer sharing network as explained here:
Share Your Printer Over a Home Network Using Windows XP
File and Printer Sharing in Windows Vista
It will mean you can use your existing printer, but the disadvantage is that whichever PC the printer is connected to, that PC must be switched on & running for any other PC to be able to use that printer.
