Would that card be able to use all of vista features? Does vista require D9 or 10X? Also, how can I tell if that card is D9 or 10X?
Vista doesn't require a DX10 card, it will run fine with a DX9 card, you just won't get the benefit of some of the subtle graphical improvements DX10 brings in games that support it.
And a DX9 card will run Aero just fine.
You can tell whether a card is DX9 or DX10 by looking at it's specs. If you're talking about your own card, find out it's model and then search for it's specs on Google.