Dual DVI out problem

I am having a problem....

I have an nvidia 8800 GTX video card with dual DVI out and an s-video
output. I am running windows vista home premium (64bit).

I have a 22inch LCD monitor and a 32inch LCD television with HDMI input.

I want to be able to connect the television to the 2nd DVI ouput on my video
card so i can sit back on the couch and play games/surf the internet. I went
out and bought a DVI to HDMI cable and hooked it up thinking that it would
work, but it didnt. The television says 'no signal'.

If I connect the s-video cable it does work. It's as if the 2nd DVI output
on my video card in not functioning.

Does anyone know what is happening? Does Vista not support dual DVI out with
my card yet?

Any help will be greatly appreciated