I don't want to sound dumb or ignorant, but I feel no matter how hard we try, we will never keep up with HDMI (unless you have a swimming pool of cash each month to throw at the latest).
But yeah, long story short, regular DVD upscaling is done best with HDMI. HD-DVD is a toss up, I use Component mainly on my A2 (my TV has no HDMI either) and HD movies look fine (for a 30" HD monitor). DVD's though, are about the same from my old Sony DVD player. On the HDMI Mitsubishi TV downstairs, it does wonders for regular DVDs.