Pc through TV

Hey guys i've been puzzling over this for a few days and have finally given up on google.

I'm trying to connect my windows xp desktop to my TV via HDMI. I'm using an nvidia geforce 9500GT in this set up. For something that I was expecting to be quite simple is turning into a nightmare.

I'm struggling to get audio through the HDMI cable. I thought that as these cables carry audio that it would just be a case of plug and play. I've tried downloading the latest drivers from nvidia and still nothing. Is there anything 'extra' I should be doing?

As a note, I have also tried taking a 3.5mm jack to phone lead onto one of the inputs and have had sound that way, but the TV doesn't have just a red and white phono input on there own, so I can't use them for sound as then I don't get any video.

If it helps i'm trying to get this to work on an LG 37LC2D TV.

Thanks