SPDIF is usually for the "headphone jack" on your case.
Anyway, I had the same problem! With a Asus P4P800-E Deluxe. Once installed Windows 7, no sound, but drivers installed. When I pluged in audio jack, the card wouldn't "see" it. I downloaded the drivers from the manufacture website, still no sound. Even installed a Sound Blaster Live! sound card, but Windows 7 doesn't support it. Drivers wouldn't install, via Windows, Install CD, or download.
I NEVER got this problem resolved!! (I am selling the mobo on craigslist or ebay. Had a huge problem with the previous seller. A whole other issue.)
I am sorry, but I believe the true root of the problem is Windows 7. Microsoft doesn't support alot of older devices, beit motherboards, graphics, sound, LAN, whatever.