I'm looking at buying a new commuter bike.

Does anyone know the stand-over height for the Windsor Oxford 51cm and 56cm? The bike is sold at Bikes Direct. I'm trying to figure out which size to order. I'm 5'10", so I assume the 56. But i read they run "big" and have a high stand-over height.

Also the tire size is 700x32C. But can you put a smaller tire, like a 700x28? Just curious.