there will be no differance as far as quality goes. I use a dvi to hdmi conector on my rig. But for me, i get no sound... says somethin about me needing an actual hdmi to hdmi cable and use the hdmi adapter that came with my graphics card to get the onboard sound.(that was a mouthful)
well, its an HDtv, so you will have your HD quality. as long as you bump your resolution from 800x600 to 1920x1080P in CCC
You might have to change your overscan/underscan, but that should be all. As for sound, you'll just have to switch your playback device. In Vista this is extremely easy, I can't remember for XP.