E521 Video Card and Dual Monitor Use

Hi

I have a Dell E521. I've bought a second monitor but it's connected to the VGA port of the video card and the picture quality is significantly lower than the other monitor which is connected via the DVI port.

I have a second identical video card to that which is currently installed in the E521. My question is: Can I install the second video card and would it enable me to attach the second monitor to the DVI output on the second video card? If not, is it better then to replace the existing video card with one that has two DVI ports?

Dimension E521 AMD Athlon 64 X2 Processor 5000 (2.60Ghz, 512K) 

Video card ATI Radeon X1300 Pro 256MB DVI/VGA output with 1xS-Video Output 

Thanks