I recently purchased a NS-L55X-10A Insignia LCD TV. I use a DVI to HDMI cable from PC's video card for video and an audio cable from PC's sound card for audio. I have video signal on TV, but no audio at all. I used to use same cables to connect my PC to my LG LCD TV in the same way and it worked perfectly.
In order to have audio while using a DVI-HDMI cable, make sure to connect the DVI-HDMI cable to HDMI 3. Then using a 3.5mm to RCA Y-Cable, connect the computer to the L/R audio ports located below HDMI 3 labeled "HDMI 3 PC Audio Input".
