No sound from HDTV with laptop connected

I was just wondering if someone could help me out. I have an samsung HDTV and a cheap Compaq Presario laptop. I get no sound from the TV when the cable is plugged in. On the back of my TV, there is a "PC Input" and an audio jack right next to it. I have the cable connected from the "PC Input" on my TV to the Monitor output on my Laptop. I also have a headphone cable ran from the audio jack next to the "PC Input" on the back of the TV to the headphone jack on the laptop. The picture is fine, but there is no sound. I have looked at all of the sound settings on my TV, and there is nothing. Also, on the sound settings under control panel on my computer, I have two different settings: "Internal Speaker/Headphone" and "SPDIF Interface". No matter which one I set to default, not sound comes from my TV. As soon as I take the cable out of the headphone jack on the laptop, sound starts playing from the laptops internal speakers. When I click "test" on the sound settings in control panel, I can see the bars moving up and down, so I know some sound is playing, but none is coming out of the TV speakers. Any help on this, thanks.