What is the make of the PC? There's a chance that the connectors for the power button, USB etc won't fit on the board if the board uses proprietary connectors. Same goes for motherboard mounting holes, size etc. But if it uses the ATX standard to the dot then of course it'll work as long as the transfer is done properly.
Do those techies work for a computer company by chance? They'll say that so you don't do anything to it and then buy a new system because you have to.