W.E.I is a microsoft tool which rates your computers processor, memory, graphics, gaming graphics, and primary hard disk. The W.E.I gives you a number which is meant to give you an idea of what software you should get for your PC. It also gives you ideas of what you should upgrade to increase performance.
Guy 1: Dude, i'm gonna buy Microsoft Flight Simulator
Guy 2: You fucking noob
, flight sim recommends a windows experience index of 5. your computer only rates 3.5. its gonna run like shit.