I am still hitting the problem with my Mach64 module:

(EE) ATI(0): [dri] ATIDRIScreenInit failed because of a version mismatch.
[dri] mach64.ko kernel module version is 2.0.0, but version 1.0 or greater is needed.
[dri] Disabling DRI.

I tried building the Xorg with servers from sources, same problem.
My next idea is to remove the version-check, but this would not be
the intended way it ought to be. Also i thought about setting
the kernel version to 1.1 instead of 2.0.0, but this is also not the
intended way.

Now after building everything from source i ask here once more for help.
(everything refers to xservers, xorgdrivers, mesa, drm....)

Debian Lenny
Xorg 7.1.1(7.1.0)
git mesa
git drm

Need help for sure, im totally lost now (except my crazy ideas about changing version numbers)