When X-Plane won’t start up, or if it crashes when exiting the program, there is a driver problem–assuming, of course, that you have a useable operating system, video card, and RAM. This is very likely an issue on Windows Vista, where Microsoft does not install OpenGL drivers by default.
Let’s start by making sure the operating system and hardware are useable.
First, the operating system (OS). Windows XP, Vista, or 7 (both 32- and 64-bit) can be used, as well as Mac OSX.4 or later. There are simply too many distributions of Linux to keep track of them all, but X-Plane has users from virtually every major distribution (Ubuntu, Fedora, openSUSE, etc.).
Windows NT can not be used due to problems with Microsoft’s joystick manipulation in that OS.
At least 1 GB of RAM is required to run X-Plane, as well as a video card with at least 32 MB or so of VRAM.
Virtually any modern ATI or NVIDIA video card may be used (anything that supports OpenGL), but an integrated Intel graphics chip is not supported. As of this writing, these chips are too slow to run X-Plane.
So, in Windows, assuming you have Windows XP or better and a video card capable of running OpenGL, and you get some sort of crash when trying to run or exit X-Plane, you probably need to update to the latest drivers for your video card. Instructions for doing so can be found on the Installing Graphics Drivers in Windows page.