Everytime I try installing my graphics card my monitor wont work?

I have an e-GeForce 6200 LE Graphics Card, and I would like to upgrade my old graphics card (unbranded) to this one (it's my step dad's old one, so i'm just trying to be able to play some WoW with him). But if I have the 6200 in, I cannot see anything on my monitor, but with my old one I can, so with the old one in, I downloaded the Driver (from nVidia website) for the GC and my system, Windows XP Pro 64 bit, but I cannot instal because it is unable to find suitable hardware. But if I use my 6200 I can't see the screen so I can't really install anything. Any help is appreciated.