since M$ splited Windows XP to Windows XP Home Edition and Windows XP Professional in the very final stages, it can be assumed that the difference is made by some simple keystrokes and mouse clicks. but (afaik) if it is differentiated by the source code, for the coders, it would be easy, but not for consumers - by changing or replacing .dlls. pretty interesting thing to try. but as fares said, problem will arise as there is a high possibility of we not doing it perfectly...
