That's true - and another reason to go with Mac.
On my Mac I can test Mac versions of Safari, Firefox, and Opera. I can also have virtual machines to test for Windows Firefox, IE6, IE7, and IE8 at the same time. If I were on a PC I would only be able to have one version of IE installed.
It's still funny to me that to develop websites that work on all of the Windows browsers a Mac is the only thing that makes sense.