Originally Posted by leigh123@linux
Nvidia support is outstanding and easy to setup , they also add support the latest kernels and Xorg server quickly .
ATI's support of Linux is extremely poor and hard to setup , they took over 5 months to support the latest Xorg server
For some time I have been using nvidia on desktop PC and ATI on a Dell Latitude D610 laptop. Until very recently nvidia support has been excellent, though there have been bad interactions with software suspend/tuxonice.
Recently nvidia seem to have done something to screw up badly, as discussed in another thread (possibly more than one), e.g. http://www.nvnews.net/vbulletin/showthread.php?t=123912
ATI have certainly improved the ease of installation of their fglrx driver recently, and also installed a startup script that automatically creates and inserts the required module if you boot up after a kernel upgrade. That worked much better than the old 'radeon' X11 driver for ATI.
However, I was having a lot of trouble getting the laptop to work with projectors for presentations. When I learnt about the 'xrandr' program I found it did not work with the ATI driver. However, it turned out that by then there was an 'ati' driver for X.org. So I installed that, and it has worked perfectly, including using xrandr to make the laptop interact properly with a variety of projectors. I don't know whether ATI contributed to that driver. It also works fine with software suspend2 (tuxonice).
So in the past I would have unhesitatingly voted for nvidia. Now I find ATI winning. But I have not tried an ATI card on my desktop PC.