Bought a Vista Powered computer yesterday and couldnt get the Vista PC to see/find the XP Shared printers. Up until then all the Vista stuff was quick an uncomplicated. I tried the Vista wizards etc without help. Then I googled and found the linked forum post and it all connected well.

Basically you:
1. Go to Control Panel. Choose printer. Then choose Add Printer
2. Choose Add a local printer. Click on Create a new port. The default in the drop down box is Local Port. Do not change that. Click Next.
3. A dialogue box will appear asking for you to enter a port name. Type in the \\computer name\printer name ie. My computer's name is XP_Lounge and the printer name is HPLaserJ so I typed in \\XP_Lounge\HPLaserJ.

Thats it. Make sure you spell and match the case for the computer and printer names.