Same problem here...
With a GF4-mx the tv-out works like a charm.
With my new FX5700 doesn't work at all...;(
Same XF86Config file. Same errors as the above.
All my cards are from asus.
Even on winloss, tv out works but it's worse than the gf4mx, in the sense that I couldn't have my monitor and my tv working together, but only one at time.
This is really awful to me because with a €70 card tv-out works, and with a €180 card it doesn't.
Please NVidia, speak up and let us know if this is a known bug, and if it has/will have a resolution.