HTPC w/Dual Tuner Card - DirecTV DVR

For HTPC w/Dual Tuner Card, relating to DirecTV DVRs and receivers. I have a DirectTV HD receiver, and I'd like to utilize my dual tuner card inputs on my Home Theater PC. I'm using a Hauppauge WinTV PVR 500 (Dual Tuner). I'm hooking this up to one television.

I'd like to be able to watch one tv show, while recording another.

The HTPC is running Microsoft's Media Center Edition (rollup 2).

Do I have to get a second receiver? Or can I use the one DirectTV receiver?

I have 2 coaxial cables coming from my Satellite Dish to the wall.