Window Or No Window?

On the issue of whether or not to display a web mockup inside a browser window when presenting it to a client:

Yes, the window takes up room, and yes, you'll have to size down the mockup a little bit more so it'll fit nicely on your godforsaken PowerPoint page. But when we're building site layouts, we design them inside a make believe browser window. Why? We take into consideration how everything looks inside it. Contrast, color, etc. Sometimes a good design loses 35% of its appeal when you kidnap it from its environment or take it out of its container.

Than again, what do I know. The Interactive Annual I got last week in the mail displays winning designs and, ..nope, no browser windows.