Hairy_hen - I just watched Philosopher's Stone on Blu-Ray with 6.1 surround, and it was pretty freakin' awesome. I'm planning on watching one per night until Deathly Hallows Part 1 comes out.
Too bad I only have the other 5 movies in DVD-resolution MKV rips. They still have the AC3 5.1 audio, though - better than stereo, at least.