My friend is coming over this weekend and we both play WoW. I got the game recently and don't have Burning Crusade or WotLK. He has 3+ characters over lv 60 including a death knight. Will he be able to sign on to my computer and use them even though I don't have the expansion? I checked his battle net account and it says his status is Wrath of the Lich King, so I think that means that the expansion CDs just unlock the content...