Yea, the Wikipedia article that lists all the games under DX10 has UT3 listed as one of them, but I don't know if there is any benefit to having DX10 vs DX9. In fact, i'm pretty sure that the game runs slightly worse in Vista than XP, and that doesn't make sense in a game that supposedly supports DX10. The update might change this, though. They are completely revamping the game engine, so it wouldn't surprise me if the DX10 support was fleshed out.