that's kind of a hard question to answer. is it a real xbox live code that gives your account gold access for 48 hours? yes. is it real as in am i mailing it? no. it's going to be emailed to the winning bidder via the listia email system. thanks for your interest.
if a person puts a high bid up but the bids haven't reached that level each bid another bidder makes will up the credit level for that item automatically until their highest bid has been met or passed. it sounds more confusing that it is. anyhow, good luck!