Haven't read the article yet. I'm gonna read that link about the various Steam options tho. Mind you, you don't need to buy a Steambox, just install the SteamOS if you've got a suitable computer.
As for spec, Toady is right that a very modest spec is more than enough to run today's games at high enough quality levels. That said, with the PS4 and XBO out soon, we're gonna start seeing games taxing hardware a lot more than they used to (hopefully/finally!) I haven't needed to upgrade my PC since I built it 4 or 5 or so years ago, it still feels new.
That Steam pad looks good tho if they can pull it off. I haven't used a PS pad for a long time, I did really like the ergonomics of it but the thumb sticks used to do kinda dislocate my thumbs a bit when I used them so they'd click I recall, long time ago now tho. You can probably get used to anything but yeah, except for a touchscreen maybe!

Playing an FPS on a tablet is a nightmare.