Well there are a few key differences with Valve vs 3DO.
1. Valve is already profitable.
2. I do not believe that they are charging Steam Box manufacturers a licensing fee unlike 3DO so that may help.
3. Reading the article, it looks like some Alienware models are able to dual boot as a Windows PC? If so, that helps justify the price. A $750 PC isn't expensive vs a $750 video game console.
2. They are not, indeed, but the other problem is that manufacturers need to make money on the hardware, making Steam Machines more expensive that consoles anyway (and more than self-built PCs as well).
3. Yes, and not just Alienware. But honestly, if you are going to put it under your TV, I have a hard time imagining people using it as a PC on their TV screen. Monitors are better in that regard, and you usually want to be closer to the screen for regular PC use.
