HDCP over DVI is possible. HDCP over VGA is forbidden. I think you know these TLAs.
So the only reason I can think of is to play Blue Ray HDCP protected content.
I need the reason(s) for using a DVI port vs the D-sub port on my Acer 22" wide screen monitor. My PC has a NVIDIA GeForce FX 5200 video card with 256 Meg of RAM and both ports. The display has an excellent picture using the D-sub at the native resolution of 1680 X 1050.
What benefit(s) will I see using the DVI port?