I have XP SP3 with a GeForce 8400gs and it has a DVI and VGA port on the back. I have one monitor plugged into the VGA and another monitor plugged in DVI via DVI to VGA adapter. Either monitor works in the VGA port, but neither monitor works in the DVI port. My PC (HP Compaq) doesn't even recognize that I have a second monitor plugged in. I went through Windows troubleshooting and uninstalled and reinstalled the NVIDIA driver, and I'm now at a loss as to how to get the PC to recognize the second monitor. In Display Settings tab, I don't even have the option to "extend the display" to monitor #2, because it doesn't think monitor #2 exists. Any help would be appreciated.