Here is another excellent article describing the steps to take in order to get a refund (from Dell in this case) when you are forced to buy Windows in order to get the computer you want.
I strongly encourage people to do this. Sometimes it will work, and you will get some money back, but often it won't, and you will either be ignored, or you will be told, as I have been, that if you don't accept the license agreement, your only option is to return the entire computer for a refund. But either way, it makes some noise and if enough people do it, perhaps some OEMs will start to pay more attention.
Why bother? Here's a simple analogy. Suppose you were buying a new television, and for the particular model you wanted, you were required to also buy a specific cable or satellite subscription. I don't think it would take long before consumers were up in arms about that.