1- Almost Famous. It's my favorite movie, so it automatically makes the list. This is technically a triple-dip, because I owned the one-disc version of the DVD before upgrading to the two-disc director's cut. A quick search of Amazon and Ebay shows that apparently it's not available in the US, but it doesn't look like it will be hard to get in a US compatible format.
2- Eternal Sunshine of the Spotless Mind. Another of my personal favorites.
3- The Godfather Collection. There's a new remastered DVD collection out, and I think it's also available on blu-ray. The original DVD collection (the one I own) isn't a very good digital transfer; the picture quality isn't as good as it could be.
4- The Matrix. I've never seen any of the sequels, but the original is just so cool. I think it'll definitely benefit from improved picture and sound.
5- Moulin Rouge! Once I'm living on my own, I won't be able to steal my sister's copy. I guess this isn't technically double-dipping, since I don't own it myself, but I just think it'll look fantastic in high def, so I included it on the list anyway.
6- Serenity. Another triple-dip. If I decide to double-dip on TV series I already own, Firefly would be on the top of the list.
7- The original Star Wars trilogy. This might not count as a double-dip, because I only own it on VHS.
8- V for Vendetta. Of my Natalie Portman movies, this is the one I think will benefit most from blu-ray.
So, Abby, which of your DVDs would you replace with blu-ray?