NOTE: This is not for playing games.
Requirements:
Must be:
Reasonable support on Linux. I don't use Windows at all on my desktop, NVidia is what I've got at the moment.
Needs to have 2 x DVI ports to run dual monitor at 1920x1080 each. So resolution for the expanded desktop would come to 3840x1080.
Nice to have:
Small form factor. I've got a mid tower case and would rather have a small card if possible.
Low power/heat - Don't really mind this as long as the spec is reasonable.