64-bit operating systems

The Current Windows Vista Logo
Windows NT included support for several different platforms before the x86-based personal computer became dominant in the professional world. Versions of NT from 3.1 to 4.0 supported DEC Alpha and MIPS R4000, which were 64-bit processors, although the operating system treated them as 32-bit processors.
With the introduction of the IA-64 (Itanium) architecture, and later the AMD64/Intel64 (or x64 in Microsoft terminology) architectures, Microsoft released new versions of its more contemporary operating systems to support them. The modern 64-bit Windows family comprises Windows XP 64-bit Edition for IA-64 systems, Windows XP Professional x64 Edition for AMD64/Intel64 systems, and Windows Server 2003, in both IA-64 and x64 editions. The x64 versions of Windows XP Professional and Server 2003 were released on April 25, 2005, while the IA-64 versions were released at the same time as their mainstream x86 (32-bit) counterparts. Windows Vista is the first end-user version of Windows that Microsoft has released simultaneously in 32-bit and x64 editions.


The next in line was Microsoft Windows 98 released in June 1998. Substantially criticized for its slowness compared with Windows 95, many of its basic problems were later rectified with the release of Windows 98 Second Edition in 1999. Mainstream support for Windows 98 ended on June 30, 2002 and extended support for Windows 98 ended on July 11, 2006.
As part of its professional line, Microsoft released Windows 2000 in February 2000. The consumer version following Windows 98 was Windows Me (Windows Millennium Edition). Released in September 2000, Windows Me attempted to implement a number of new technologies for Microsoft: most notably publicized was "Universal Plug and Play." However, the OS was substantially criticized for its lack of compatibility and stability.[4]
In October 2001, Microsoft released Windows XP, a version built on the Windows NT kernel that also retained the consumer-oriented usability of Windows 95 and its successors. This new version was widely praised in computer magazines. It shipped in two distinct editions, "Home" and "Professional", the former lacking many of the superior security and networking features of the Professional edition. Additionally, the "Media Center" edition was released in 2003, with an emphasis on support for DVD and TV functionality including program recording and a remote control. Mainstream support for Windows XP will continue until April 14, 2009 and extended support will continue until April 8, 2014.
In April 2003, Windows Server 2003 was introduced, replacing the Windows 2000 line of server products with a number of new features and a strong focus on security; this was followed in December 2005 by Windows Server 2003 R2.