Day of Defeat: Source; Black and White
Day of Defeat: Source
What you see here is what you usually see with X1800 Crossfire. The general rule, as with all performance enhancements as significant as doubling your GPU rendering power, is that you get to turn on IQ where you couldn't before, or you get to jump up a notch or two on resolution without sacrificing the IQ levels you had previously. Just more go, basically. In Day of Defeat, you can play with IQ on (6xAA and 16xAF) at any resolution we test, and maintain a Vsync friendly framerate.
Black and White 2
In Black and White 2 you get the IQ levels for free, the performance with a second board outstripping the basic results of the single one. Admittedly that performance scaling is odd and unobvious, but it's what you get.