Hi Sid, Unfortunately it's not looking to good for Vista drivers for the conextant/riptide. Just going by your PC specs, I'm guessing that card is relatively old and that no Vista drivers exist or ever will.
From the screenshot, it looks like Vista hasn't even detected a physical card. Have you tried Control Panel/Add hardware and pointing the install to where you know the drivers are? It's a long shot....
I can only assume you've already maxed out all the sound levels for the AC97? Right-Clicking volume icon/Playback devices/ac97**/properties/levels? Although from personal experience the AC97 output will always be on the quiet side.
Sorry I couldn't you