In Microsoft Windows XP Service Pack 2, Microsoft is introducing a set of security technologies that will help to improve the ability of Windows XP-based computers to withstand malicious attacks from viruses and worms. The technologies include network protection, memory protection, safer e-mail handling, more secure browsing, and improved computer maintenance. Together, these security technologies will help to make it more difficult to attack Windows XP, even if the latest updates are not applied. These security technologies together are particularly useful in mitigation against worms and viruses. This document specifically focuses on the changes between earlier versions of Windows XP and Windows XP Service Pack 2 and reflects Microsoft’s early thinking about Service Pack 2 and its implications for developers. Examples and details are provided for several of the technologies that are experiencing the biggest changes. Future versions of this document will cover all new and changed technologies.