I was thinking about getting an MSI also and i was a little worried about the PSU fitting inside, but, if you wanted, it's techncally posible to leave the PSU outside the box and just drill some holes or something. It's kind of ugly and jury-rigged, but if you absolutely NEED a way to do it, then that's a possibility. Maybe you could do some fancy wire-work and mount connectors to the outside of the case to plug the PSU into from there so that there aren't any gaping holes in the side, and also to keep the cords from straining the connectors on the mobo and H.D and misc parts. This is what I'm thinking about doing.
Also, I talked to Keypower recently (last week) and they quoted me $130.
Why the hell are they so expensive when you can buy a regular atx PSU for $40? Is it doing something special or is it just because these are a sepcialty item?