The first DVD that I viewed on my first digital projector was The Sound of Music
in August 1999. (This "5 Star Collector's" Edition had just been released by Fox, and my whole family was dying to see it!)
What a disappointment! I almost took the projector back to the dealer that very day.
Fortunately, I soon discovered that all the edge-enhancement "halos", "blooming", and poor black levels were unique to that transfer.
The next DVD that I tried was The Mask of Zorro
, and it looked like "film". (well ... close to it anyway!)
I ended up keeping the projector ...
If you're asking for a good demo disk to try, almost all of the recent transfers that I've seen from the main studios have been magnificent, but "Seabiscuit" was a huge standout on my system (currently an Infocus X1).