Considerations for Multibooting with Windows 2000 and Windows XP
Contributed by mikejc 
August 24, 2004 
Tagged: Windows installation
4.0 in order to support an older application. With multibooting, you can choose which operating system to run or specify a default OS if no selection is made during the restart process.
Some good info from Microsoft. A computer can be configured to let you choose between two or more operating systems each time you restart the computer. For example, you could set up a server to run Windows 2000 Server most of the time but allow it to sometimes run Windows NT Server.
Before using the multibooting feature, consider the tradeoffs: each operating system uses valuable disk space, and file system compatibility can be complex if you want to run Windows 2000 on one partition and Windows NT Server 4.0 or an earlier OS on another partition. In addition, dynamic disk format introduced in Windows 2000 does not work with earlier operating systems. However, multibooting capabilities are a valuable feature providing the single-machine flexibility not only to run earlier operating systems but also experience the advances in the next version of the operating system, named Windows XP for the client version and currently codenamed “Whistler” Server for the server version.
Ed:
For a detailed walkthrough of the process, check out seamonkey’s guide for setting up a PC with multiple operating systems