My computer has no audio?

I'm pretty adept at computer hardware but I can't figure this out. A few weeks ago my sound stopped working. I don't think anything odd happened around the time it stopped working, and I didn't do anything I don't normally do. There was a Windows update I think, but I don't see that being the cause right? Here's what I've tried so far:

1- I made sure the sound wasn't muted and all of the other obvious stuff like that.

2- I made sure the speakers worked on another computer, they do.

3- I downloaded and installed all the latest drivers for my motherboard.

4- I opened up my case and looked for visible signs of damage

5- I opened a program that shows a bar that bounces up and down to show volume to see if my computer knew it was supposed to be making noise - it does, the bar jumped around.

6- I checked every audio out. That's when I discovered that the front headphone jack works, so I made due with it for a while until I ordered a dedicated audio card.

7- I installed the Creative Sound Blaster Audigy today - basic PCI sound card. Yes I installed the software that comes with it, yes my computer knows the sound card is there. It doesn't work.

8- I opened the SB diagnostic tool thingy and it said "The audio device supported by this application may not be present or may be operating in an unsupported mode"

9- I moved the card to a different PCI slot - got the same results.

10- I got on Yahoo Answers because I'm officially out of ideas.