This is not possible. Even if an emulator for windows was made on the android platform it would be like trying to run Crysis on windows 7 on old 300Mhz pentium CPU. the differences between Android being a unix/linux system and windows not being one aren't the only problems, windows isn't yet made to even run on the ARM processor architecture.
You would need to emulate a different CPU and operating system and emulating stuff is extremely inefficient, you lose a large portion of performance. On top of that lost performance you are already trying to do this on an already very slow processor of a tablet... sorry but it will not work with the way things are right now.
There are even more problems but I think the point is made. It is theoretically possible to emulate pretty much any system or any other system but in use the performance hit is so great and on a tablet there already isn't much performance to begin with that it isn't practical to make a windows emulator on any phone/tablet device.