the problem described about using fgl_glxears is one of shared memory - you must use tmpfs. two steps to fix this, assuming you have finished installing the ATI drivers (fglrx).

1) ensure the driver is actually running - lsmod should list fglrx.
if not, return to 1, until true.
2) [ as root ]: edit /etc/fstab to contain the following mount:
tmpfs /dev/shm tmpfs auto 0 0
3) [ still as root ]: mount tmpfs
4) run fgl_glxgears and enjoy.

Notes:
a) i have not found a way to make the ATI driver install survive a kernel re-build/compile. Thus,
after reconfiguring the kernel, you must re-install the ATI driver and, unfortuantely, restart X.
b) for some reason, on my system, tmpfs doesn't actually auto start at boot, and i have to manually mount it ...
c) you should really run fglxconfig after installing the ATI drivers.

good luck ...

-daniel