Is it possible to setup Xorg with two ati cards ?
Just for fun, tried to setup X.org with xf86-video-ati(from git) and two ati cards - 2600xt and 4850(init card).
So far - no luck(kms or non-kms), I created a custom xorg.conf with two screen sections, each with own monitor/device, xorg crashes with it, then it calls ubuntu's tool to reconfigure graphics configuration, and that thing crashes Xorg and freezes pc.
Didnt know things that bad with multiple cards in Xorg.
This config works fine with other OSes.
Multiple GPU support with the open source drivers is still tricky, although there is work being done in that area.
For now your best bet is probably fglrx.