How come no new dual core smart phones like the Galaxy S2 don't have windows XP running on them?
The phones are very powerful and I think it would run great on these.
Or is it better just to have the new Windows Mobile?

XP was written to run on a specific hardware platform. Not the sort of hardware that is found in Smart Phones. So it would need pretty major surgery to get to work on a Smart Phone.

So may as well write a new operating system specifically for the job than try and bodge something that was never designed for the task onto hardware it was never meant to run on.

Equally, the method of input needs to be taken into account aswell. XP is designed to be operated using a mouse and keyboard - actions and gestures don't transfer easily to a touch screen device. Click and double-click, fine, but what about right-click, drag, scroll-wheel? Basic things like Ctrl+C to copy, Alt+F4 to close a window, PrtSc to do a screengrab then suddenly require a virtual keyboard as big as your face to accommodate all the extra buttons. And running any XP-native program on a 4", 800x480 display would just be utterly unworkable.

So in short - even if it COULD run on a smartphone, there is no sensible reason why it SHOULD.

Smartphones use ARM chips (because of the low power consumption) which Windows XP does not support.

Windows 8 however does run on ARM chips and will be capable of running on smartphones.

It has been done before but I would hate to think how fast this thing would chew through it's battery.

http://www.gsmarena.com/itg_xpphone_...-news-3593.php

Here is a video of the XPPhone running Windows XP

http://www.youtube.com/watch?v=o7irMplW88A