Most original Xbox games are not in the public domain. Downloading "HDD Ready" sets likely violates copyright law in your jurisdiction. However, Archive.org’s stance is that these files are for preservation and research on hardware that is no longer commercially supported.
Best practice:
Some Xbox games refuse to run from HDD due to proprietary streaming. HDD Ready packs often include “patched” default.xbe files. Here are the notorious titles you should source via Archive.org: xbox hdd ready archiveorg
The "HDD Ready" label is useless to a stock, unmodified Xbox. The original firmware does not allow the execution of unsigned code or games from the hard drive. These archives are designed for the modding community, specifically for those utilizing: Most original Xbox games are not in the public domain
Your Xbox must be formatted for large drives: Best practice: Some Xbox games refuse to run