Correct me if I'm wrong, but there is actually very little difference in the quality between Component/DVI & HDMI on most TV's. Possibly the only thing that's going to make any difference between them is 1080p as I have a feeling Component doesn't run at that res.
For the HD audio, that's only useful if you can send that output from the TV to a surround receiver or your TV handles surround sound and lots of speakers. Personally, I prefer taking the digital optical direct to my receiver, and I don't think there is any difference between that and audio via HDMI.
Hey Foetoid, the only thing that makes me very nervous of Digital Delivery is the reliance on the hard drives... having been in IT for 20+ years, I've seen (and experienced) my fair share of hard drive crashes! :^)