Should you replace your DVDs with Blu-ray?

[Blu-Ray Hunter]

I have a fairly sizable collection of DVDs (~400). Back in Jan, I took a gamble on Blu-ray and bought a Sony BDP-S300. Then, the war between Blu-ray and HD-DVD wasn't completely decided, however I got a sweet deal. I got the player and 10 free movies (five instant in-store selections and five through the mail). I tried to pick titles that I didn't already have on regular DVD. I've now got around 30 titles on Blu-ray.

I find myself really questioning which Blu-ray disks to purchase. Some titles I'll buy without question (i.e. Lord of the Rings, any Pixar releases, etc.). I really hate spending the extra money on a Blu-ray disk for something I already have on regular DVD, especially if the quality is not worth the extra price tag. For example, my Blu-ray player will up-convert (to 1080i) all of the regular DVDs I have. So the real question is, why spend $30 (or more) on a Blu-ray disk when I can get the same title at Wal-Mart in the $7.50 bin on DVD? Or, why replace a DVD that I already own with Blu-ray if the quality is not immediately noticeable? For example, I already own the movie Castaway on DVD. In looking at the Blu-ray version, I can't tell a noticeable difference in the picture. You can in the sound, but not the picture.

I buy Blu-ray disks for one reason, quality. How can you tell (from the back of a Blu-ray case or another method) if an older movie was shot in HD quality? What's going to make me run out and buy "American Graffiti" on Blu-ray when I know the movie wasn't shot in HD? I have the double-throw-down-anniversary version of the movie Jaws on DVD. I'll have to think twice about replacing it with a Blu-ray, if/when it comes available.

Thoughts?

On an ending note, if you like nature, you can't go wrong with the Blu-ray versions of "Planet Earth" and "Galapagos". Picture quality and sound are unsurpassed. These two are a must have for any Blu-ray owner.