As has been said before here, there is the option to have a sword in your left hand if you want, it would just take some getting used to having the primary attack button as the left trigger instead of the right.
Hmm. You know, I might have to play "lefty" just to keep from being confused..... since, right now, Oblivion is right click to block (with the shield in your left hand), left click to attack (sword in right hand). So to keep the block & attack matching, if the mouse buttons are matched to your hands, I'll need the weapon left / shield right.