Microsoft Knowledge Base Article 314644 contains the following summary:
This article describes how to configure your Windows XP
desktop to communicate with your mobile devices. This article also describes
how to synchronize all of your devices so that all of your files are current on
all of your mobile devices and on your desktop.
Windows XP simplifies synchronizing information on multiple mobile devices. You can share files and information from your desktop to your various mobile devices, such as your Handheld PC or Pocket PC.