The Microsoft Download Center page Microsoft Shared Computer Toolkit for Windows XP contains the following overview:

Shared computers are commonly found in schools, libraries, Internet and gaming caf├ęs, community centers, and other locations. Often, non-technical personnel are asked to manage shared computers in addition to their primary responsibilities.

Managing shared computers can be difficult, time-consuming, and expensive. Without restrictions, users can change the desktop appearance, reconfigure system settings, and introduce spyware, viruses, and other harmful programs. Repairing damaged shared computers costs significant time and effort.

User privacy is also an issue. Shared computers often use shared accounts that make Internet history, saved documents, and cached Web pages available to subsequent users.

The Microsoft Shared Computer Toolkit for Windows XP provides a simple and effective way to defend shared computers from untrusted users and malicious software, safeguard system resources, and enhance and simplify the user experience. The Toolkit runs on genuine copies of Windows XP Professional, Windows XP Home Edition, and Windows XP Tablet PC Edition.