I just bought a Samsung dual format HD-DVD/Blu-Ray player on eBay. It is a factory refurb, 90 day factory warranty, and was $359. I don't own any Blu-Ray discs yet. I'm filling in my collection with HD-DVDs and will buy new releases on Blu-Ray and stuff by the two studios that never released HD-DVDs. You can get both at places like CD Exchange or off eBay for reasonable prices.
BTW, I agree about Planet Earth. It's fucking amazing in HD.
Another thing I have found is that the quality of upscaling of regular DVDs varies wildly. Some stuff looks like it was mastered from a cell phone video theater bootleg (Spurs videos and anything Trek related), and some stuff actually upscales to 720p, which looks pretty damn good for regular DVD prices. The Matrix box set and the Stargate SG-1 and Atlantis series all upscale quite well.