WIndows Vista was created in the year 2007 by the Virussians. It is a virus designed to look like an OS. Using Vista will cause your computer to crash a lot of times in a nanosecond.
Otherwise, Windows Vista is an operating system used by Microsoft PC's.
Windows Vista, in real life, was created in 2007 by Microsoft. It is an operating system designed to have Windows Aero (for Authentic, Energetic, Reflective, and Open), a set of interface and design guidelines that were introduced by the real life Windows Vista operating system. It has been negatively reviewed by most people. It's internal name was Longhorn, but in 2006, it was called by its current name, Vista. It was known to be quite unstable, and very few PCs could actually run it at the time. This caused Microsoft to rush out Windows 7, which was what Vista should have been.
In many universes, Vista is known to be the most evil Operating System in the world, and using it can cause numerous problems for the user, from System crashes, to BSoDs, to other terrible things.
The name ViSTA stands for Virussian Spy, Tracing and Annoyance, while Vista in real life has no secondary etymology.