I have 3 monitors, all of which use DVI or VGA (the third is a TV which does have HDMI input, more on that later). I have a gtx460 SE graphics card with two dvi outputs and an HDMI output.

I also have an extra 8600gs graphics card. Can I use the 8600 for an third DVI output? I'm hesitant to use HDMI for the TV, because I tried to do so on a friend's set up and the audio output was horrible (worse than the standard 3.5mm stereo jack used with VGA). The TV does not allow you to select a different audio input while using HDMI, and I do not currently have a receiver in the set up for the TV.

I am afraid the 8600gs will not work as a secondary with the gtx460 because the drivers are different for 8-series cards. Is there any way I can get this to work without switching the TV to HDMI? Any have a good experience with audio-out from the HDMI port on a recent nvidia card?

Thanks.

Possibly, not definitely. Throw it in a spare slot and see what happens.
Sorry, My original post was pretty stupid so I edited it, and now it's nothing useful.

AFAIK, DVI is HDMI sans audio. The problem could be unique to your friend's setup, too. Try it yourself.

I use speakers and a headphone jack.

If you're using Vista, you won't be able to use Aero unless both cards are the same. On 7, this shouldn't be a problem. On XP it doesn't matter.