The Add Printer wizard installs only the print driver for Windows 2000 when you add a printer. If you're sharing that printer, it's possible that other users on the network who have different operating systems (Windows 9x, for example) might want to print to your printer. If they don't have the necessary printer driver for their operating system, they won't be able to print. You can configure your system to include the printer drivers for those other operating systems, making them available for download and installation when another user connects to your printer for the first time. After the printer driver is installed on the remote computer it can print to your printer.
Although the Add Printer wizard doesn't give you the option of adding drivers for other operating systems when you first set up the printer, you can add them afterwards.