I assume you mean that your newer Original Xbox Games don't work on the Xbox 360?
Well it may be due to the version of the Emulator on the 360 being old and so it needs to be updated.
Here are two ways of updating your Emulator version on the 360:
ONE is through Xbox Live - Same process as previously stated for other answer, this is the easiest and most simple way to update the emulator.
TWO is via downloading the update and burning it to a cd or dvd which is then placed into the 360 drive.
The place where you manually download the Xex file is from:
Scroll down the page to locate the download link.
Thanks to [Dionm] for this tip on the forum.