I did try the ITV HD v. Upscaled DVD experiment.
One problem with this comparison is that the ITV HD broadcast was 16:9 and the DVD is widescreen with black bars top and bottom.
This makes it hard to do a direct comparison.
Initially I thought the DVD quality was much better, but when I used the DVD zoom to remove the black bars, it was apparent that the ITV HD picture was actually a bit better.
However, the surround sound on the DVD and lack of advertisement breaks meant we quickly switched onto the DVD to enjoy the film.
One thing to note; Episode I/II have been shown before on ITV HD, and the quality of episode II is much better than episode I