The Gentoo install moves apace. I've got rid of the annoying keyboard error on login (had the wrong settings) and now I've got the two screens running seperately under the default Xorg Radeon drivers (see screeny). I've as yet failed to get direct rendering working though. I think I need a more recent DRM driver than the one currently supplied by the Gentoo peeps. I could also try the official ATI drivers, but they apparently won't do 3D acceleration with two screens (or I couldn't find the correct settings when I last messed with them on Ubuntu).