yeah just wait until FEAR and STALKER comes out and probably even Area 51 to some degree, don't get me wrong it'll still look amazing like HL2 did even on my FX playing DX8.1, but it'll be those fine subtle details you won't see.
In lego star wars they use HDR and SM3.0....with an ATI card you aren't able to see the little blur effect when a light saber is swung....so like I said basically it'll be all the fine details that make it more realistic you'll probably be missing.
That's retarded that they have a massive card like the X850 and no PS3