Why can't Windows 7 recognize my new soundcard?

I am at such a loss with this issue and I really hope someone can help me. I'll do my best to give as much information as I have.

Okay. So, my father-in-law built me a new computer for Christmas. Everything is perfect on it, except that the soundcard it came with {Realtek AC97} doesn't work. That's fine, I bought a new one { 4 Channel PCI Sound Adapter Card - AC97 3D Audio}.

I disabled the Realtek soundcard in the BIOS, then turned off the computer and install the PCI card. I then turned the computer back on and waited for Windows 7 to recognize the hardware. It never did. So I went ahead and installed the drivers from the CD it came with. The drivers installed just fine, but the card itself still isn't recognized by the computer.

In the Device Manager, there are no yellow or red issues to be seen; when I click on the sound option under Device Manager, it says "This device is working properly." I even tried "Check for hardware changes" and nothing happens. In the bottom right corner of my taskbar, there's a big red X next to my sound options. It says "No audio output device installed."

My speakers are plugged in and there's power running to them. In fact, I get a crackling noise whenever I attempt to play sound from the computer.

I know that the soundcard is working because I installed it on another computer and it recognized it immediately {running Windows XP, mind you}.

Advice? Questions? Comments?

Thank you all!