I'm trying to set up my two monitors on this hp5750 machine. Here is the output of lspci | grep VGA:

01:05.0 VGA compatible controller: Advanced Micro Devices [AMD] nee ATI RS482 [Radeon Xpress 200]

As far as I understand ATI no longer supports this card in Ubuntu 12.10. That's not a major problem as the free drivers work fine, but I am stuck with the mirrored option. If, in system settings, I unselect 'Mirror Displays' and click apply, I just see a lot of nonsense on the screen and then I just wait for 30 seconds for any changes to be undone.

I've done some searching around but the only answers I've found have to do with settings in Catalyst, which I don't think is an option for me. Is there any hope?