A Happy Birthday is in order for Microsoft Windows as today, November 20, 2006 the operating system turns 21. 21 years ago - on November 20, 1985 - Microsoft was releasing a 16-bit graphical operating environment called Windows 1.0. 21 years later, Microsoft's multi-tasking GUI-based operating environment is Windows Vista.

At that time, Windows 1.0 came with a price tag of $100 and required 256KB of RAM, DOS 2.0 and two floppy drives and had been announced for two years. The press kit released by Microsoft contained a squeegee and a washcloth for Windows.

A consistent volume of features and utilities now taken for granted - such as Calendar, Notepad, Terminal, Calculator, Clock, Windows Write and Windows Paint, Control Panel - have debuted with Windows 1.0.

Windows 1.0 made a whole two weeks on the market before it was patched. Microsoft's first operating system offered little support for both devices and applications on its initial debut. Compatibility with Excel and Word was added in 1987 and 1989.

Windows 3.1, codenamed Janus, hit the shelves in March of 1992 and was the architect of Microsoft's success.