It should work. Just make sure you get a video card with an actual audio chip in it. A lot of them rely on something else to produce the sound.

As for the CPU, you want something fairly fast. It is better to get a faster dual-core processor than a slower quad core for this application.

I use a AMD 785G chipset motherboard in my HTPC. It has everything on the motherboard. I added a low-end Phenom X2 and it works great. The only problem with it is that I have to use the optical out to get digital audio to my receiver since the HDMI port only supports 2 channel stereo.