When my friend visits, can he just download his Xbox 360 gamer profile from Xbox LIVE to my console?
Technically, yes. But we urge him—and you, when you roam—not to do this. Unlike your gamertag on the original Xbox system, your gamer profile can exist only in one place at one time, so downloading (or “recovering”) your profile to a friend’s system will invalidate the version of your profile that’s still on your Xbox 360 hard drive, endangering any offline achievements and game saves since your last visit to Xbox LIVE.