260.x drivers don't work with external display with ubuntu 10.10 and Quadro FX 3800M
With the older 256.x series external display works fine, but it's little suspicious solution as the driver requires the ignoreABI option. When trying to enable external monitor for mirroring both display graphics become distorted and the only way to get back is to boot the x server without the external display setting.
With 256.x drivers the performance is sluggish and for example switching between gnome-terminal tabs takes few seconds and either firefox or google chrome are not very snappy. Performance is little better when subpixel smoothing of fonts is turned off. I'll be happy to give more details or try out some beta versions..