Is the steam controller natively compatable with the Windows run steam games? Why didn't they just have the Steam OS use Windows if they were gonna include it in some steamboxes anyway? I'm looking up steam big picture mode now. If it doesn't mess with the ease of use and it's not insanely more expensive, I'll probably go with that.

That's a good question. Most PC games have plug and play support for 360 controllers now, and I believe PS4 and soon Xbox One controllers as well, but I'm not sure about the Steam Controller. But even if it's not supported it should be pretty easy to remap controls to the Steam Controller I'd think. 

As for why Steam didn't go with Windows for SteamOS, it's partially because Gabe Newell seems to hate Microsoft these days, and partially because they would have had to pay Microsoft for those Windows licenses themselves or else sell the Steam Machines at a higher price to consumers. Gabe Newell's stubborness may have killed Steam Machines, we'll have to wait and see. Maybe he'll be able to convince more developers to make games for Linux. 

There's probably gonna be drivers for it on the windows version so you may not have to worry about controller compatibility but don't quote me on this. As for steam machines not bundled with windows, that's due to Gabe Newell's dumb hate for windows 8.

There's one more thing you have to do such as installing windows on your steam machine ...

I thought he said that Windows was already installed on those particular Steam Machines?

I'm not sure if it will be or not. It's possible if not likely that some of the Steam Machine manufacturers will offer a dual boot Windows 8/Steam OS option for their Steam Machines.

I think some modders have already made a driver to get the Wii U Pro controller working on PC, but I don't think it would have plug and play support with PC games, you'd have to map the commands to the controller yourself for each game, but that wouldn't really be that hard.

I've looked into that option myself since I want to get a PC for my living room. The problem is that most gaming PC's are vertical and large, not really fit for the living room. Steam Machines are horizontal and use those mods that allow you to turn your graphics card sideways, parallel with the motherboard,  which makes the cases thinner, ideal for entertainment center shelves. In my searching I never found any prebuilt, reasonably priced, horizontal gaming PC's, before Steam OS was announced. I may get a Steam Machine myself and go dual boot Windows 8/Steam OS. But first I want to see some reviews for each manufactuter's Steam Machine.

I own a Wii U and don't plan on buying another next gen console unless it has free online. Since that's not gonna happen, I was actually thinking about investing in a Steam Machine. Is it a good idea? I really don't care to learn the ins and outs of P.C. gaming, but I'm afraid it won't really be supported. I was planning on getting one of the Alienware boxes. Any advice? Is it a good alternative for someone who just cares about Nintendo like me?

EDIT: I'm not building or buying a P.C. I'm not getting a PS4 or XBO. Those aren't options. Please stop trying to convince me. I just want to know "Steam Machine good or bad." I don't care what you think is better, because I clearly don't think they're better.

He said he didn't want to tinker with shit so that's not an option. =/

That's not the kind of tinkering I'm talking about. As long as I wouldn't have to like install any extra software to get it to recognise the Pro Controller in the first place, I have no issue spending 1 minute mapping the controllers. Or I can just buy an XBO controller.