OS X 10.4.11 hosting USB printer; Vista machines need to print to it

"Enable printer sharing on your Mac (System Preferences > Sharing). Make sure the printer is on and able to print.
On the Windows PC, download and install Bonjour for Windows.
On the Windows PC, run the Bonjour Printer Wizard. You’ll see a window listing available printers, including the Mac’s shared printer. Pick it and pick a driver."

"This is from a similar question a few days ago.

Turn on printer sharing (Mac)

Detect shared printers with Bonjour 2. Detect shared printers with Bonjour (Windows)

Install the printer's driver 3. Install the printer's driver (Windows)

Send documents to your new printer 4. Send documents to your new printer (Windows)

If you do want to go the Samba way, here's Apple's official help document on printer sharing with Samba or Bonjour.

5 The last and final step is to connect to your printer from the XP machine. The instructions on how to do this can be found here."