Kernel 3.0: Working: 285/280.xx/173 current-5000 series/96xx-gf2/4 (?). Unknown: 71xx
Kernel 2.6.38/39: Working: 285/280.xx-270.xx/173 current-5000 series/96xx-gf2/4 (?). Unknown: 71xx
Kernel 2.6.36/37: Working: 280.xx-270.xx/260xx/173xx-5000 series/96xx-gf2/4 (?). Unknown: 71xx
-----------------------------------------------------------------
Xorg 1.11 - Buggy, partially working: 285.03/280.13, or newer. 
            No support: 173.14.3x, 96.43.2x, 71xxx ( that means 5xxx and older cards)
Xorg 1.10 - Working: 285.xx-270.xx, 173.14.30, 96.43.20, or newer. No support: 71xxx.
Xorg 1.9 - Working: 285-260.xx/173.xx/96.xx. Support uncertain: 71xx
Xorg 1.7 - Working: 285-260.xx; 173.xx; 96.xx. Support uncertain: 71xx
Xorg 1.6 - Working: 285-260.xx (6-9xxx cards); 173.latest (5xxx cards); 96.latest.
Xorg 1.6/1.7+ + 71.xx.xx (early nvidia and some GeForce 2): not known
Use nouveau driver and see if that works: sgfxi -N nouveau