I think I covered my question in the title. Right now both monitors are mirrored (both 19" at 1440x900). I guess what I need to know is do I need the ATI proprietary driver or will the open source driver from Ubuntu (additional drivers) work?
I want to expand the desktop between the two monitors. Still finishing install and running updates now, I just wanted to gather all documentation and downloads prior to doing what is necessary.
Any help will be greatly appreciated.