Windows MECommercial Letdown Windows ME was released in the Summer of 2000 and was the last of the Windows 9x series. It was a commercial failure and was not well received by the public. It was known for its instability and lack of features and was very unstable and a massive storage hogg. While new features were added, such as System Restore, the features were simply underdeveloped and was not enough to save the OS from being a flop. It also controversially removed the ability to boot into MS-DOS real mode, which was a massive blow (especially to the business and gaming community) and forced the running of older DOS software to be run within the Windows environment. Thankfully Windows ME would be shortly replaced by Windows XP in 2001.
Windows XP/Server 2003Homerun for Team Microsoft Windows XP was released in the Fall of 2001 and was a massive homerun for Microsoft. It was the first consumer OS to be based on the NT kernel and was a massive leap forward in terms of stability and security. It was also the first OS to be released in 64-bit (Which came out in 2003) and 32-bit versions. It was also the first to be released in the Home and Business editions, streamlining Microsoft's OS lineup. Featuring a completely redesigned GUI named Luna, it was a massive hit with the public and was the most popular OS for over a decade. On the Server 2003 side of things, it was released in multiple editions and was very popular for businesses and enterprises. Adding Active Directory, Group Policy Management, and .NET services. Windows XP and Server 2003 were some of the most successful OS's Microsoft ever released, and wasn't properly replaced until Windows 7 in 2009.
Windows Vista/Server 2008A Drag of OS Windows Vista was released in the Winter of 2006 and was a massive flop for Microsoft. When released, there was massive gap of time between XP and Vista which caused Hardware makers to not have the proper parts readily available to consumers as the new OS came out. With the new Aero UI which while pretty, was a big resource hog, it was extremely buggy and bloated OS, with more bloatware than what was expected from Microsoft. The creation of User Account Control (UAC) was a massive annoyance to users and still is in Windows to this day, while now it's more of a minor annoyance. The OS was critically slammed and many journalists called Microsoft out for its poor quality and lack of notable features. With some articles claiming Microsoft to be copying Mac OS X and its new features poorly. Thankfully on the Server 2008 release, many of the troubles of Vista were not present and new features like Hyper-V, Failover Clustering, and new Server Management software made it a good OS for the enterprise user.
Windows 7Spring Cleaning Hit Windows 7 was released in the Fall of 2009 and was a massive hit for Microsoft. It was a massive improvement over Vista and was a much more stable and secure OS. A refresh to the Aero UI was made and was much more streamlined and less resource-intensive. It included Windows XP Mode for running older software and was the first OS to include the Windows Touch features. The addition of PowerShell and XPS made the OS easier to develop on, and the addition of BitLocker and AppLocker made the OS more secure. It also added SATA AHCI support, TRIM support for SSDs, and USB 3.0 support which future proofed the OS for a long time. It also added sRGB color management, Direct2D, and DirectWrite for better graphics performance. Updates to existing apps made the OS very easy to migrate to and in turn, the OS was very popular and was the most popular OS until Windows 10 came out in 2015.