Ok, well I'm still on AGP and I bought the best card I could possibly get for it just today. However, I'm having a few problems with installation.
I insert the card and screw it in. When I boot up the computer, I seem to get a neverending BEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEP from the card. My monitor turns on but as soon as I plug it into the card, it will shut off. What could be the problem? I think it has something to do with my system power supply, but I'm not sure. If I am not mistaken, this is a power supply:

It says I am supposed to plug my 4-pin connector into my system power supply, but I find it in the case and there are no 4-pin slots for it. There are slots for the 4-pin connectors but they look as if they are my CD drives and one of them is my hard drive. I find the component with the fan and the power switch on the side inside the case, and find no 4-pin connector slots. Please help me out.
Edit: The problem was my power supply! It was not connected correctly. My graphics card came with a 4-pin cord, so I connected one end of it to the card and just tried to find a slot for it with the other end. I tried for about 2 hours, nothing worked. This time, I used my brain. There were cords coming out of what I thought was the power supply. 4-pin cords, one end already connected to it. I connected the other end to my graphics card and it worked. Geez, give me an extra cord to confuse the hell out of me! I'm really sorry guys for wasting this forum space. I tried so long before, went to a friend's house, came back and got it the first 5 minutes. Anyway, I'll be off enjoying my new card now! Peace!