I know i am a bit late but a tip on the cow level: You can play it in norm, NM, and hell. but dont kill the cow king in norm until you have killed the end boss in nm. as long as you dont kill the king you can always come back and get more XP (this is espesialy useful in hell where they dish out tons of xp). when you are finaly done with the hell boss you can keep playing the cow level over and over again to get xp (just dont kill the king). when you are really strong you can then go back and kill mephisto and baal over and over again with alot of MF items to help you get cool stuff.
Bruce