redford

With the HD players and titles now arriving, I know I will eventually purchase one, but I would like to wait till prices drop.
In the meantime I will probably slow down on my DVD purchases and wait to buy the movies on HD DVD.
During this waiting period, I thought it would be a good time to buy some classics I want.
My question is which movies can be HD? Doesn't the movie have to be originally filmed in HD? Or can anyone movie be converted to HD?
I don't want to buy a title and then find out it will be available in HD.
Any help would be greatly appreciated