Main thing to think of is read and write limits..
XP uses a swap file that duplicates memory ( that will have to be disabled )
There have been MANY MANY threads on this..
consensous is to use XP Embedded.. which is just an image of the operating system stored on solid state media..
also, some Microsoft components freak out once they see " removable media "
XP embedded is very expensive for the designer, but lic is only $90
Other than that, search for more info here, there is tons