I had 3 accounts and used my brother and girlfriends account for over 1-2yrs no problems I was only multi-boxing in instances though. SOON AS I started my 70 shaman group and was pvping in arenas I got 3 accounts banned for third party use and had to fax in proof of ownership(I got all the accounts back). Moral of the story have 5 accounts all in your name or none at all. Since then I bought a new TBC box X2 and rerolled 2 shamans to replace those 2, and 5 horde on magtheridon .