Video Card Problems

I need help. I'm having a hell of a time getting the video card in my desktop to work. A few weeks ago, I tried to turn on my tower. It powered up fine, but the monitor indicated "No Signal" when I turned it on. I unplugged everything and plugged everything back up and it worked fine.

A couple of days ago, I had the same problem again, but this time, unplugging the cables did nothing. I made sure the video card was seated properly, but still, same issue. I took it to my office and had the IT guy look at it. After removing the copious amounts of dust, nothing had changed. Due to some discoloration to the PCB on the card, the IT guy came to the conclusion that the card was probably fried. I should let you know that this card was the stock card in my HP machine, an nVidia GeFoce 7500LE. Well, this was an OEM card, so I couldn't order an exact replacement. I got an nVidia GeForce 8600GT from NewEgg and tried to install it. No luck. I tried every possible combination of driver installation/uninstallation. I tried reseating the card, reseating the RAM, turning off the on board video, everything. I know the computer works fine, because the TV out on the motherboard itself still works, but no matter what, the video card will not work. If someone has a similar problem or has an idea of what I could do, I'd grealty appreciate any advice. I'm about to drop the whole thing off a very, very tall building.

Thanks.