When you say you purchased a VGA cable with audio, the audio portion is a separate 3.5mm connection, correct?
If it was a resolution problem, then you'd see "Mode Not Supported" displayed. But if you're receiving "No Signal", it means that the TV isn't detecting a signal of any sort. You might checking to see if there's an update for your video card.
I purchased a highly rated VGA cable with Audio and connected it from my new tv to my laptop. In the control panel for my video card (NVIDIA GeForce Go 7600) it recognizes an attached "Samsung" display and I've tried the Clone and Dualview settings, but no amount of tweaking has since resulted in my TV displaying what I'm seeing on my laptop. I've tried hitting fn-F7 (the one that shows LCD/-> ). When I select PC from the source menu it takes a moment, then says No Signal. I'm not getting audio either. I'm not able to turn the volume up or mute or anything in PC mode. The little red light just keeps blinking at me. Thoughts?