People, keep asking why they would want a Steam box. I think you hit the nail on the head. Preconfigured, pretested, and optimized to run games. I go over to peoples houses and watch them boot their computer for 10-20 minutes into Windows just to play a game. It's obvious they don't know how to build or maintain their systems. I have been using Linux as my main desktop since about 97. Admittedly early on it was because I was a tech junkie, but I really don't work on my systems very often. My wife even switched to Linux this last year, and the amount of maintenance headaches I've had since then have dropped ten fold. I know there are people who have had nightmare issues with Linux, and I know people who have had none. I also know people that can't keep a Windows computer running properly for more than a few days, and even more that think it's normal to wait 3 to 5 minutes for an app to start.
But excuse the rant. I think the point is that if Valve is going to sell a steam Box, that you could dual boot with windows if you want(or not), or install other applications to use it as a desktop(or not). That will just work day in day out, without the fuss of windows. People will buy it.