2000: Windows Me
Screenshot courtesy of GUIdebook.
Windows Me (also called Windows Millennium Edition) was released in September 2000 and quickly became one of Microsoft's most criticized operating systems because of installation problems, bugs and hardware and software incompatibilities. It introduced Windows Movie Maker. Critics maintain that it was introduced only for marketing purposes, to give Microsoft something to sell for the 2000 holiday season.
Windows Me was the last version of Windows that included the DOS architecture. It lasted little more than a year, until Windows XP was introduced. Windows Me required a 150-MHz Pentium processor or the equivalent (a 300-MHz model was recommended), 32MB of RAM (64MB was recommended) and 320MB of free hard drive space (2GB was recommended).