|  | Upgrading to Windows XP Professional Upgrading Computers Running Windows 2000, or Windows NT Workstation 4.0 SP 5
| Because Windows 2000, Windows NT Workstation 4.0 SP 5 and Windows XP Professional share common registry, file system, security, and operating system kernel structures, nearly all applications that run on Windows 2000 and Windows NT Workstation 4.0 SP 5 will run without modification on Windows XP Professional. Upgrading from these operating systems to Windows XP Professional is easier than upgrading from other Windows operating systems because: Almost all peripherals and devices that worked with Windows 2000 Professional and Windows NT Workstation 4.0 will work with Windows XP Professional. The version of NTFS used in Windows NT Workstation 4.0 is automatically upgraded to the version of NTFS used in Windows XP Professional during the upgrade process.
| Note: A few minor incompatibilities exist between the version of NTFS used in Windows NT Workstation 4.0 and the version of NTFS used in Windows 2000 and Windows XP Professional. For example, file system filters used by anti-virus software and third-party networking software that were originally written for Windows NT no longer function between the two versions of the file system.