Just wondering if it is acceptable to discuss legitimate dvd back ups here. I know there is no real way to distinguish between those who have purchased the dvd and those that haven't - which is why I wanted to double check before discussing the subject further.

Yes, you can discuss backing up movie DVDs here.

Read: http://forums.xbox-scene.com/index.php?showtopic=279708
Although that's primarily game-related, it applies to movie DVDs as well.

Basically, you can discuss backing up movies you own. You can only make one legal backup of any DVD you own. Discussion of backing up rentals or, to an extreme, downloaded movie DVDs will earn the poster a ban. Offering or requesting files will have the same effect: a ban.