Thanks for the replys. I just wanted to make sure they didn't take a step back to make another one forward in compatibility.
But since you asked, my 184.108.40.206 machine is Windows Media Center XP, with an LG +/- dual layer burner (SATA) and a Philips +/- dual layer burner (IDE)(same failed results on each drive backing up Las Vegas Season 4, Disc 4).
220.127.116.11 machine is XP professional with LG DVD read-only drive (gave successful results) and LG +/- dual layer burner, both SATA.
I agree, different drives give different results. In the past, I have seen similar success on each machine, usually trying both with a difficult discs, rarely with different outcome. While the drives, machines and results are different, both had LG SATA drives and XP. Maybe similar enough, maybe not.
The one difference that stood out for me was the DVDFab version.