Well, to tell you the truth, I'm pretty sure that if you encode your movie as KDVD with a calculated average bitrate to fill that disk, it's going to look pretty damn good
I have a 32" Samsumg HDTV, and I put 3 movies on each DVD, and only in some places I can clearly see some artifacts. But of course, it depends a lot on the movie.
But overall quality, it looks almost like the original DVD.
As a matter of fact, I have some original DVDs that look worse than my KDVDs, when viewed on the HDTV
These DVDs I haven't even bothered converting them to KDVDs, because I know the result will be worse.
The best thing you can do, and I suggest you do it, is encode that movie as KDVD and burn it, then go to a store and play it on a HDTV.
Then you'll know what to expect from your future encodes.
-kwag