You can open the disc tray and place the DVD in the XBOX 360 and hit Play. It will read the DVD disc and present you with an option to play your movie unless it is a burnt copy and in a ill-regular format which in this case the standard XBOX 360 drive firmware won't be able to read it.
no
Not sure about the original xbox.But the Xbox 360 can
YES!
I am Pretty sure it will, As the slim is an upgrade form the lower 360 platform so as long as you have the update from xbox live you should be able to play doom 3 on the 360 slim
no it does not only dvds
yes the xbox itself will play regular dvds
You Can't.
NO the ps3 does
If it works on a DVD player, it works on a xbox 360
No, you cannot play blu-ray dvds on any version of the xbox 360, it only plays regular dvds Correction: It can Play Regular dvd's along with HD DVD compatibility
yes but not blu ray ones