HDMI has digital audio, I have DVI to HDMI cables already. I have a half-baked idea to also splice in my digital audio from PC side so I don't have to use a separate audio system from the HDTV. Pinout diagrams for the HDMI seem obtuse. Any ideas or pointers welcome.
Some HDTV's will have separate analog audio jacks for one of the HDMI inputs. Just run analog audio out of your PC using a standard headphone jack to RCA adapter. Analog audio is more than good enough for TV speakers.
I just went through this myself, and I too had an 8800GTS. I sold it and bought an ATI Radeon HD4830 for $100 shipped (brand new). I'm a nVidia guy all the way but ATI has an adapter with many of their Radeon video cards that is a DVI-to-HDMI adapter. This adapter will pass both the audio and video signal, and the audio is in the HDMI uncompressed 7.1 surround sound format. I don't have my system completed yet but I have read all over the net that these cards do a wonderful job of doing what I have described. Best of luck ~