Microsoft Flight Simulator X, also known as FSX, is the latest version of Microsoft Flight Simulator

Microsoft Flight Simulator

Microsoft Flight Simulator is a series of flight simulator programs for the Microsoft Windows operating system, although it was marketed as a video game. It is one of the longest-running, best-known and most comprehensive home flight simulator series...

after Microsoft Flight Simulator 2004. It includes a graphics engine upgrade as well as compatibility with Windows Vista

Windows Vista

Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

, having been marketed by Microsoft as the most important technological milestone in the series to date.
It is the first version in the flight simulator series to be released on DVD-ROM.