I have a legit copy of Windows Xp home edition. However, I was wondering if this version can be converted to professional version-- with the appropriate different files?

it could be ,but my advice dont because whenever you come for the activation part it is ganagive you some troubles for checking the dll files and you will see things you dont have to deal with ,so my advice install xp corp and that set.

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... :unsure: