Basically the picture is a little better but the biggest thing (to me) is you do not have to adjust the size of the screen with dvi. With vga, you have to shrink it, move it left, right, up, down, and my personal favorite, pitch (i could never seem to get it straight
). Dvi puts the screen exactly on the monitor with no spaces in between the picture and monitor panel. You still control the brightness and contrast though.
New graphics cards don't even come with vga connectors anymore (only dvi to vga converters).
So dvi is the way to go now.