OK reason

kram36
Oh I have looked at this, for my brother. He was looking at the Alienware Alpha. I priced him together a system using a 1TB hd, faster cpu, memory, gpu and could beat the Alienware Alpha cost. Plus using Windows so the vid card can be taken advantage of.
 
But I see you had a different approach to your build. I have to ask though, does the SteamOS not store the games on the HD? A 128Gb as you used can be filled quickly with very few games.

OK why only 128GB. That is a very good question. My reason is that SteamOS is unlike any Linux OS I ever tried Its a game console layout and I don't need all that room when you stream your game from PC to Steam Machine. That is also the reason for using the GTX 560 2GB. You see then graphics are already rendered on the PC when streamed to the Steam Machine. And sense I have a fantastic network I get no lag doing this. So I choose to keep it light. You can make it as large as you want . That is up you. plus you can also have a external drive with every thing on it that you share between your PC and your SteamOS .  Its not like any OS you have ever used it hard to compare or label. You just have to try it with out any operating system or duel boot for your self to see its full potential. Until you try it all by its self its difficult to explain. Its very user friendly give it a try its kinda fun.
 
So when you stream you get your DX and when you don't you get a new kind of API other then everything else out there. Its new.
Plus Streaming anything my PC has is kinda cool. I do movies games and music from it all the time.
 
Options for a non stream version can be a easy thing. Bigger drive and a GTX 760 4GB would still be low cost and work fantastic. No one will stop you if you want to get bigger card too. I have used a GTX 780 6GB SC too. Its all Up to you Just make sure its a good card and it will always be great fun.
If you want to know what its like try the option in your steam account (Big Picture) use it with a Xbox 360 controller. That is as close as you gonna get to getting a feel of what its like. 
 
Thank you guys for your positive comments all of you!

Um let me state an overlooked appeal to the Steam Machine. Your at your buddy's house whom has a steam Machine and you want to play your game on your PC but cant go home. You can log in to your account and play your own games from your library. you can bring a usb3 external library of your games too.. Also over looked if you don't want your family on your computer playing your games . Have them play your games on the SM with family share. While your play your games on your pc at the same time.