The shader effects tend to be more accurate as well from what I've noticed (usually it's easiest to see in fog)
Which may or may not be a side effect of DX10 capable cards being of significantly more power than your average DX9 card of course, but I wouldn't know that offhand.
Anyway, Steam detects actual cores, not HT 'cores.' I wouldn't think too many people would be gaming on an Atom anyway.