definately go with DVI if possible and affordable. maybe a little background will help.
with a standard hd15 output, the video card must convert a digital signal, to analogue, send it through the cable.. then if using an lcd the lcd than must take that signal and convert it back to digital and then process it for display. this conversion to analogue on the video card side was needed with CRT designed monitors because CRT monitors use analogue methods to produce the picture, thus needing an analogue signal. but LCD's require a digital signal. so it's necesary to convert that signal back to Digital on the LCD again. needless to say... what a waste.. and the more conversion / use of analogue the greater chance for interference.
as for DVI. it's purely a digital link. it is actually a 2 way communication pathway in digital form. the Video card does not need to convert any signal and outputs it in it's digital form along the cable to the LCD display which takes it and uses that pure digital signal. the added bonus of DVI is it's 2 way as I said. which allows the computer / video card to receive information from the display, such as type, settings and limitations. this provides a cleaner, crisper, faster and better signal.