jfree, a big welcome to you to Sevenforums!
On both Windows 7 and Vista, make sure under advanced sharing settings (find by typing phrase into start menu search) that you turn on network discovery and file and printer sharing (both computers).
On the Vista one (without the printer installed), in the start menu search bar, type 'add printer' without quotes and click it. Go through the steps to search for and install the printer driver (and thus the printer) to which you are connecting.
Hope this answers your question. Let me know if it does or not.