You can either
A) Buy a new video card with full HDMI port
B) Buy a DVI->HDMI cable.
FYI, DVI-->HDMI will not carry audio.
I know this because my Sony HDTV did not have a DVI input, only a VGA that would have just brought the resolution down. So I went on Amazon and got a DVI->HDMI cable. Now I have full native 1080p.
Try it out !