Asus M2N-SLI MB w/ Diamond Radeon 1600Pro graphics = no 3D/Beryl

I was recently given the aforementioned MB and cannibalized one of my machines for additional parts including the Diamond Radeon graphics card. I've been playing w/ Mepis 6.5 b7 for several days and cannot invoke the KDE 3D option at sign in. When I try, the screen just returns to the sign on page. I've tried switching to the xorg Radeon driver but when I do I get no GUI, only a blank, black screen. I've run the "glxgears -printfps" successfully but can't log in for 3D as stated above. I've seen multiple post regarding difficulties with Asus MBs......Ideas?

MM