Apple Bonjour for Windows runs on Microsoft Windows 2000, Server 2003, and XP.
Apple describes Bonjour as:
Bonjour, also known as zero-configuration networking, enables automatic discovery of computers, devices, and services on IP networks. Bonjour uses industry standard IP protocols to allow devices to automatically discover each other without the need to enter IP addresses or configure DNS servers.
You can find more information about it at:
Note that Apple has a caveat that some VPN client software may interfere with Bonjour.