Windows XP (Windows version 5.1)

Windows XP (Windows version 5.1) becomes a predecessor of Windows 9x/ME as well as Windows NT/2000 and is available for 32-bits CPUs in the following versions:

- Embedded
- Home Edition (1 CPU) for private user (Oct. 2001)
- Professional Edition (2 CPU) for business user (Oct. 2001)
- Media Center (1 CPU) especially for multimedia devices (Nov. 2002)
- Tablet PC Edition especially for Tablet PCs (Nov. 2002)
- Server Edition (4 CPU)
- Advanced Server (8 CPU), also 64-bit Intel CPUs
- Microsoft Windows Fundamentals for Legacy PCs (July 2007)

A 64-bit version of Windows XP was announced officially of Microsoft in April 2003. The RC2 was available in February 2005. Windows XP Professional x64 was published in April 2005. At most 16 gbyte RAM are utilizably with that, the virtual address range enlarges to 16 tbyte.