If your aim to do fast cows, you should definitely look at War Cry barbarian. It requires very little gear and its very effective, especially against cows.

The War Cry skill damage has been buffed this patch and the skill itself stuns the cows, so you dont need to worry about defense and go full out on offense (Again, assuming you'd like to mainly do cows)

As you get better gear and using a tanky mercenary you can even start to do other Inferno parts of the game.

There is a great guide on this build on Wiki:

http://annihilus.net/wiki_index.php?...heap-Expensive