Using Dell desktop as "audio receiver" with new sound card

In my office, I have several audio sources -- a TV with audio outputs, XM radio, an iPod, and my computer (playing Launch! customized radio). I had thought about buying a receiver and speakers and plugging them all into that so I could have a centralized audio system. But my partner has convinced me that I should connect them all to my Dell desktop and make THAT act as the centralized receiver.

He thinks that I can install a SoundBlaster Audigy2 ZS Platinum Pro card, plug them all into the card as audio sources, play everything through my computer speakers, and then control which source is playing and volume and such all from my desktop.

I've looked at the card, and it looks like it's designed for true audiophiles, and I'm afraid that once I plug everything in, it will only mix the sounds internally, not act like a receiver and let me just play the audio sources through my computer.

Anyone have any experience with this? Any input on the best solution here?