While Xi3’s Piston may only be a Steambox through its software optimization, that still leaves us with a milestone on our hands now that the system is available for pre-orders: it’s the first Valve-blessed PC on sale. If you’re willing to set aside just under $1,000 ($900 during SXSW), you can claim a Big Picture-friendly mini PC with an embedded, 3.2GHz version of AMD’s quad-core A10 in addition to 8GB of RAM and a 128GB solid-state drive. There’s no mention of the conventional spinning storage referenced at CES. Expansion is limited to larger-capacity SSDs, although that’s not surprising when the entire computer is smaller than a GeForce GTX Titan. The real jolt will be the launch timing. Xi3 won’t have Pistons shipping until around the holidays, which could leave some of us hunting for less-than-official (if considerably larger) substitutes for the full Steam experience.