I have built an HTPC, which uses Nvidia 7600GS card. TV is a Toshiba 72MX196 (72" 1080p DLP).
After extensive testing and back and forths, I have concluded that using HDTV out on this card (which connects to Component In of TV) is far superior to using the (very tempting) DVI-->HDMI link. Believe me, I did try to calibrate TV for each input using all the reference images and "guides" I could get my hands on. I even have a DVD that walks you thru calibrating your tv using its controls.
1. Desktop text and icons are the only two things which look better with DVI
2. Colors thru HDTV Out are richer and deeper than DVI.
3. Video (moving images: movies, TV [thru ATI Elite], etc) is richer and *more* detailed on HDTV Out. DVI has a washed out or slightly out-of-focus look. Doesn't look as detailed.
4. This is very annoying with DVI: When you hook up your TV to the HTPC using DVI-->HDMI connection, image adjustment controls (which let you move your image up/down/left/right so that it's centred) are gone! I have seen this when using DVI to hook up to my desktop NEC monitors, but it was never an issue. But with TV's it is!!! I have read quite a few forums, and the missing controls (in DVI mode) to centre image on TV's seems to be haunting a lot of people with various makes and models of HDTV's.
It could be that I am missing something, but based on my experience I would recommend that stick with the HDTV Out port Nvidia has provided on the card. It is there for a reason. DVI output is NOT meant for TV's, and it shows. May be that some of the artifacts I saw won't be a big deal or too obvious on smaller screen TV's, but on a large TV, it is VERY obvious!.
By the way, in case someone is wondering, my HTPC is Core 2 Duo E6300, with Windows MCE 2005. I am also running Nvidia PureVideo. And I used both classic and modern interfaces of NVidia control centre. And I did play with *every* fricken setting it had to offer...