Laptop: (I don't have Vista, so these are for Windows 7, which should be pretty similar)
Right-click Computer, choose Properties.
In the 3rd section on the right, check the workgroup name. If it's not the same as the one you noted on the pc, click Change Settings. On the Computer Name page click the Change button. In the Workgroup field type in the workgroup name exactly as it appeared on your other machine.
Click OK to close that window, and OK again to close the previous one.
You may be asked to restart your computer, if so do it now.
Double-Click Network
You should see both your laptop and your PC listed by name. Double-click the PC.
You should see the printer on your PC. Right-click and choose connect.