Yes, what you are running is called a DVI-to-VGA adapter from your video card. Its what I did when I built my tower last christmas that had a x1950PRO, but my old monitor only ran VGA.
I think if you got a new monitor, you'd see a very big difference. Not only because DVI is faster and crisper, but because the monitor itself would have a better response time and a higher contrast ratio. So when you combine a nice monitor with DVI, you'll get basically no ghosting and great color. A new monitor would compliment your graphics card quite a bit. I know mine did.