Apple ads against Vista

At one point, Apple made a serious of ads against Windows Vista.
How come they can get away with talking trash about other company's product? Isn't that supposed to be illegal?
I wonder if Microsoft sued Apple after the commercial were aired on television.

I thought the same thing at first but it looks like you can actually criticize a competitor's product on TV.
Microsoft has done the same thing with some Apple products, but it's always Apple who is trying to trash Windows.