PS2 and the Xbox were two of them
Some Xbox game do work, and some dont.
Some only if you have the Xbox 360 Hardrive and some software downloaded from the Xbox 360 to the Xbox.
I don't think that you can play an original Xbox game on an Xbox 360 live. But some games from the old xbox you can play on Xbox 360.
XBOX Classic game usually refers to the old XBOX games for the first XBOX system. There is now a 360 system. Some of these are available on XBOX Live in the Arcade section.
Some you can, some you can't. If it is a newer xbox game it probably can.
You can trade in your Xbox in most game stores and some websites.
Gamestop will clean some xBox 360 game discs.
If you have the "newest" save on the game. And you delete an older save it will be fine. I've done it before and it helps out with the memory space on the Xbox. And be useful if you want to put music on the Xbox. :)
candystand.com is cool theres addictinggames.com but that sends viruses it crashed my computer you can go on a tv stations sites such as Disney or cartoonnetwork that's what my sister goes on or nick.com you should get an xbox
Only some Xbox games
It depends on the game because some games are region sensitive and some aren't.
No it is not a PS2 game. Ninja Gaiden is a Xbox game. There is also a Nintendo NES version of the game. It was released for Xbox in June 2004. There are some newer version of the game and they are available on the Xbox 360 and PS3