Do Original Xbox Games Work on Xbox 360? (No – Limited Backward Compatibility Only)

No. The Xbox 360 uses a different CPU architecture (PowerPC vs. x86) and a proprietary emulator that only supports ~600 curated titles. Your original Xbox discs will not boot.

Check the official backward compatibility list – if a game isn't there, it won't run. No hacks or updates can add unsupported titles on stock hardware.