Besides, DX10.1 is no big deal. It just optimizes textures, AA, and sound.
I agree with what Vaanish said. The current DX10 cards are not fully compliant with DX10.1....Only cards like the GeForce 9 series and so forth, are fully compliant with DX10.1....I've heard though, that DX10.1 is backwards compatible with DX10.