This article provides important details about the Xbox Live accounts and content on an Original Xbox console when the console is sold.

Any Xbox Live accounts, premium content, and saved games that you have saved to your Xbox console will remain stored on the console if you sell it, unless you clear them from the hard disk first. However, the person who purchases your Xbox will not be able to use your Xbox Live account as long as you have cancelled your subscription to Xbox Live. Optionally you can set a user pass code to help protect the account. It is recommended that you clear all data off of the hard disk before selling your Xbox console.

Note that unless you deliberately delete your premium content from the hard drive, however, the premium content will be playable even if the new owner does not have an Xbox Live account.