I have vista home premium and i used to have windows media center. but alas i dont. not on this pc. not sure how or why or when, but it dont exist. I'm using an xbox as my device(extender) and I have another PC (laptop) that I've set up to use windows media center and that works fine (laptop has windows 7).
So I know sometime (probably while I was trying to tweak my shared folders perhaps) I must have deleted or uninstalled it.
But you'd think I'd know that wouldnt you?