As I posted above (hasn't shown up yet due to moderation) xmodule=svga works (sorta) and Knoppix 6.0.1 worked by default with no special boot parameters.
I don't think there is anything special about a moderately old GeForce 7600GS or PCI Express that would make this card unsupported. Something has changed between 6.0.1 and 6.4.3 to break this though.