@Psionic Roshambo, Go with a custom BIOS chip. It can allow you to play games region free and re-enable Mil-CD support. They can also run debug executables from the Katana dev kit.
@K3Nv2, The Dreamcast format is different to Windows executables. In this case, the main executable is "1ST_BOOT.BIN" and is either signed for a debug kit or retail console, and is usually scrambled.