I'm wondering this myself right now, mostly because of the special Best Buy has this week. I can get the HD-DVD drive for my Xbox 360, which is the cheapest HD-DVD player out there right now, and it comes with the first season of Heroes on HD-DVD. On top of that, I can mail away for 5 free HD-DVDs. They're movies that I'm at least interested in and Heroes I haven't watched yet but am anxious to.
There are a couple of things holding be back, however. First, this who Bluray vs. HD-DVD battle is far from settled and it seems like either format still could come out on top. Ideally I would like to go with a dual format player, but they're pretty expensive still. Getting locked into a losing format would really suck.
And speaking of locked in, I'd be starting off my Heroes DVD run in HD, which is expensive as all get out. The standard DVD set of the first season is like $40 but the HD set is between $60 and $100. So I'd be throwing down at least that much for each subsequent season. Also, HD movies are far from cheap in comparison to standard DVDs.
But man, do I ever want to watch HD movies on my 57" HD TV. Sure, my Xbox 360 upconverts my standard DVDs to look better than they should, but the pure clarity of straight HD would be so amazing. I'm so on the fence right now...