On a XBOX 360 u can but on a the old XBOX's i think you have to buy a thing to plug into it
If you wanted to watch HD DVDs on the 360 you would have to buy the extra external HD DVD player. This does not make much sense now because HD DVDs "lost" the format war to Blu Ray.
no
Yes - though depending on where you purchased your Xbox 360, you may or may not be able to do so.Region 1 DVDs are designated to be played primarily in North America (Canada, U.S), U.S. territories, and Bermuda.If you purchased your Xbox 360 in any of these areas, you should be good.If not, you can watch it on your PC.
Not sure about the original xbox.But the Xbox 360 can
YES!
NO the ps3 does
No, the Xbox 360 elite only plays DVDs like all other models of xbox.
If it works on a DVD player, it works on a xbox 360
yes the xbox itself will play regular dvds
yes it dose to 720p or 1080p
yes but not blu ray ones