This integration note provides system engineers and network administrators with tested information to upgrade successfully from Microsoft Windows NT 4.0 and Microsoft Windows 2000 to Microsoft Windows Server 2003 with Microsoft Service Pack 1 (SP1) applied on HP ProLiant servers. This document includes information on planning, preparing, and upgrading their existing operating system to Windows Server 2003 with SP1 applied. The focus of this document does not include installing new installations of Windows Server 2003 SP1. For information of this nature, refer to the integration note titled “Implementing Microsoft Windows Server 2003 with Service Pack 1 on ProLiant servers.” Microsoft Windows Server 2003 is a Windows operating system that takes the best of Windows Server 2000 technology and makes it easier for you to deploy, manage, and use. In 2005, Microsoft delivered Windows Server 2003 Service Pack 1 (SP1) to enhance security, increase reliability, and simplify administration of Windows Server 2003. Windows Server 2003 SP1 provides refinements and supplies cumulative system patches to Windows Server 2003. To effectively plan for the change, you need to understand the differences between your current configuration and your Windows Server 2003 SP1 configuration. Moving from Windows NT 4.0, DNS becomes the primary method of name resolution and your network administration becomes much more granular and localized. It might seem extremely complex at first, but good planning eliminates much of the difficulty.