If my bandwidth wasn't so...ded, I would send you the FF theme you mean. It's actually called Final Fantasy. I have an orchestral version of it - it's pretty.

I still wasn't too thrilled at it in the end credits of AC, though. At the end of AC the music went swiftly downhill from Cloud's Theme (LOVELOVELOVE) to Final Fantasy (...muh, especially compared to Cloud's theme) and finally to CALLING (GAH SWITCH THE SOUND OFF).