You can do a fresh install of Windows over the top of your current install. What it will do is put everything back to what it was. That's saved me a couple of times.
You can also try de-installing the sound card completely (remove it from device manager). When you get a prompt, tell windows to get rid of the drivers. Then reboot, and it should find the card again. Tell it what drivers you want to use at that point. Alternately, you can install the old drivers specifically; don't agree to the "use the drivers on disk" question, but specify the exact one you want to use.
Beats the heck out of a format... but not by much
