VGA is an analog signal and DVI is digital I always preffered digital over analog
I switched several years ago and for me it did not change all that much because i have an older LCD but the new ones seem to benefit more from the change
I am sure some of it is personal prefferance but if you just e-mailing and word processing its not a big deal but i think if your gaming and surfing the net to sites that have high quality images and or photoshoping and editing stuff DVI my be a nice choice
if you have a video card with a dvi connection on it it is not that expensive to buy a cable and change