Hi delltrainer,
I took my G51 apart and I took pictures. The problem is not a win7 issue nor an OS issue in general. The company that makes the headphone port for ASUS is a company based in Colorado Springs, CO and the ports are simply defective. They must have a mnaufacturing problem. I took the whole laptop apart to get to the headphone port PCB board. It's a PCB about 4" long and 1" wide. It has 2 USB ports, the headphone port, the microphone port, and a S/PDIF port. The headphone port pins were in fact bad. I contacted ASUS CS and they said bring it to BB since BB is the authorized service center. I brought it back to BB and they say that they are not authorized to service the ASUS laptops but they can only offer an exchange or store credit. I accepted the store credit and returned the laptop.
The laptop is frankly a real waste of money. You can get a similar priced laptop from Newegg.com for about the same price or a little more with a core i7 720qm CPU and NVIDIA 240m GPU which might not be as awesome graphics wise but still a hell of a better deal since the CPU far kills the core 2 duo. Bring yours back and shop Newegg. You'll see a better deal and you can still get financing through Newegg.