Yeah, I bought in to HD-DVD because the Xbox 360 player was relatively inexpensive, and that's what Transformers was on. I had no choice. :)
And to my surprise, Amazon has given me a $50 credit for my pain. So given that, I think my "loss" was really only around $200 if you count the discs I bought. Meh. It's not a little money, but it's not like I went nuts buying discs.
The truth is that after renting movies on the Apple TV, I wonder how much longer I'll continue to collect. I mean, granted, it's nice to just bust out Lebowski when I want to hear, "Phone's ringin' dude!"