Unless it's just analog DVI on the DVI to DVI end, then you wouldn't notice a difference. But for most cases, you will have better quality using pure DVI. And if I'm not mistaking, VGA can not go wide screen, if that makes a differece.
Well it's my first computer build and I spent all my time researching stuff that's in the computer haha. Didn't really focus on the monitor too much. I would have assumed that it would come with a DVI cable as it shows that I should plug one into the computer in the manual however I couldn't seem to find one in the packaging O.O
Right now I am on a 20" LG at 1680 resolution and everything looks fine. Just was unsure if games would look better it I got a DVI cable.
I wouldn't worry too much about it... As long as you can hit the native resolution of your monitor then you probably won't see much improvement. I just know my 19" LCD TV can only hit 1024x768 or something like that using VGA, not the native 1440 x 900.