Xbox 360 Backwards Compatibility
Todd Holmdahl, Corporate Vice President of the Xbox Product Group recently answered a series of questions at xbox.com having to do with the backwards compatibility of the Xbox 360. Todd is responsible for the design, engineering, testing, and manufacturing of all Xbox consoles worldwide and is one of the "founding fathers" of the Xbox program. Since the program's inception, he's helped create the vision for the program, led the console design, development and manufacturing effort, and recruited and developed an exceptionally talented team.
Backwards Compatibility
He stated that the Xbox 360 is backwards compatible with over 200 games, missing only a few of the major titles - and that could change over time as game developers help out. Backward compatibility on Xbox 360 is done through software through an emulator (free to developers). Each original Xbox title is then certified by hand to run on Xbox 360.
Gamers can get the latest software updates from Xbox Live, burn a CD from xbox.com or sign up on Xbox.com for a snail mail CD delivered to your home (nominal shipping and handling fee would then apply). Once you get generate or receive the CD, you simply put it into your Xbox 360 and that's it. The emulation files are small, generally less than 5MB in size.
Click Here for the Current Unabridged Backwards Compatibility Game List
Original Xbox Games in High Definition
Here's the BIG news: Every backwards compatible Xbox game will be playable in high definition. Every original Xbox game will be upscaled to 720p and/or 1080i, and will take advantage of Xbox 360's anti-aliasing capabilities, delivering a picture that is clearer and crisper than anything available on the original Xbox.
Backward compatibility was deemed very important for the next-generation Xbox. To make this possible, the Xbox 360 needed to emulate the Xbox hardware entirely, including the Xbox CPU and GPU. This was only possible via software emulation due to the new architecture.
The three-core architecture in the CPU and the powerful GPU demonstrates the flexibility and power capable in the new system. Hand certifying each game ensures that it lives up to the Xbox 360 team's stringent quality guidelines and receive backward compatible status (non certified games will not play).
Hard Drive Required
Xbox 360 comes standard with a 20GB hard drive accessory which will enable gamers to play original Xbox games. Those who choose to buy an Xbox 360 Core System will want to purchase a hard drive if backward compatibility is something they want at a later date. The Core System is strictly for those who just want to play Xbox 360 games, sign on to Xbox Live using a memory unit, and enjoy the digital media capabilities of Xbox 360. You can then play Xbox games from an existing Xbox console (and some people have no legacy games to speak of). Gamers can buy the Xbox 360 Core System and add the hard drive accessory when they're ready.
Xbox Live Arcade
Current Xbox Live Arcade games are not compatible with Xbox 360. Xbox 360 is continuing to support Xbox Live Arcade games, however, and current Xbox owners will be able to enjoy new releases in the future.
Saved Games and Transferability
Content will not be transferable from Xbox to Xbox 360, including saved data and downloadable content. To help with this issue, all free downloadable content for original Xbox games plus premium content for Halo 2 will be available on Xbox Live Marketplace for free. Xbox 360 owners will be able to get this free with an Xbox Live Silver or Gold membership.
Even on the current-generation Xbox, downloadable content cannott be transferred from console to console (legally). For example, if you have two original Xbox consoles and want to have a specific asset/file download to each one, you really need to download it twice, and that means paying for it twice if it's premium content. This same limitation holds true for the Xbox 360.
Playing Games Across Platforms
Since the Xbox 360 can do emulation - including online games there was always the question of whether the hardware would support users playing against each other online using the different boxes. You can indeed play backward compatible original Xbox games cross-platform from Xbox 360 to Xbox. This should make for some interesting experiments and supposed handicaps.
Read more at: http://www.xbox.com/en-US/games/backwardcompatibilityfaq.htm