For my new media computer, I chose a nVidia GT 430. It's cheap at $80, small, and doesn't require big power connectors used by my older gamer card. It's also another nVidia card, which has some level of support for Linux.
Debian Squeeze runs Linux 2.6.32, but the 430 is new enough that it requires newer drivers to work well. I wasn't looking forward to dicking with the kernel and/or X settings just to be able to use my computer. It's easy to spend hours or days tweaking things that might help, or might not.
For additional challenge, the video card takes over the audio. The nVidia card can transmit both video and audio over the same HDMI cable to the TV. This is cool because I can control computer audio via the TV remote. However this means I'd switch from my nice Mackie studio monitors to the little speakers inside the TV.
So, under normal Debian with the new GT 430, graphics are old VESA style: low resolution and sluggish. And, no audio at all -- not through the HDMI connector, nor through the motherboard's audio port. But the video is usable.
To verify Debian with new kernel would work with the 430, I found a derivative: PureOS. Installing to a USB flash drive didn't work very well, but it gave me enough confidence to redo the kernel in my main Debian hard drive. http://pureos.org/index.php?lang=english
Upgrading the kernel turned out to be rather easy and not risky. It's in two steps:
1a) "pin" the system so it sees both stable and unstable packages. It'll use stable most of the time, but the newer files are available if needed.
File /etc/apt/preferences, add the text in bold:
Package: * Pin: release a=statler Pin-Priority: 1001 Package: * Pin: release a=squeeze Pin-Priority: 100 # JM: Package: * Pin: release a=experimental Pin-Priority: 69
1b) tell the system where unstable packages are located
File /etc/apt/sources.list, add text to the end:
# JM: deb http://ftp.debian.org/debian/ experimental main contrib non-free deb-src http://ftp.debian.org/debian/ experimental main contrib non-free2) install the new kernel. It automatically adjusts the boot manager so that you can use either the new or old kernel when the computer boots.
aptitude update aptitude install linux-image-2.6.37-trunk-686 reboot
With our system running Debian with an upgraded kernel, we're now ready to install the nVidia drivers, thus making our video card happy