In reply to:

What I don't get is why I can get 1080i and 720p via a component cable from my digital cable box, but I need a DVI to get the same resolution from a DVD.




You'll never get that resolution from DVD. The format doesn't support it.

In reply to:

Are there going to be any DVD players that outbut 720p or 1080i via component cables?




The DVD standard does not include resolutions above 640x480. You will never get better than that from a DVD. You may get an HTPC or DVD player that uses a scaler to output in that format but the information itself is still 640x480.

In reply to:

My TV doesn't have DVI connections.




For DVD, unless your TV is inherently digital (plasma, LCD, etc), I don't believe you'll see a difference. At that point, the only advantage would be transporting the information digitally so that the end product has a pure source. At 480p, I doubt enough degradation can occur in component to make a difference.