As stated before, Burrell is extremely streaky. That said, if you can afford to leave him on the bench during his cold spots, I'd definately take Burrell and play him when he's hot. If you cant waste the extra roster spot, I think Ordonez is the way to go. If he is healthy (which is still a big question mark), Ordonez will definately outperform Burrell for the rest of the year.
Oh, and next time, try the Trade/Draft/Waivers forum. It keeps the Leftovers full of relevant information to all.