First thing I noticed about your build is that you have the Prodigy "M" selected, the "M" is a larger version of the Prodigy that will support a micro-ATX motherboard (it will still support a mini-ITX board though). There are a few things I would personally change with the build but I'd expect decent game play from it considering the budget. You might look at the builds in the Systems section - specifically
http://www.tomshardware.com/forum/id-2842555/steam-machine-build-600.html and
http://www.tomshardware.com/forum/id-2842547/build-750.html
The Corsair CX "Builder Series" PSU's are entry level PSU's that, although having decent performance (good voltage regulation, low ripple and noise levels), may be short lived* due to the use of cheaper capacitors in the secondary, this review may be helpful http://www.hardwareheaven.com/2013/05/corsair-cx600m-power-supply-review/6/ (conclusion page). It would work if I can't find something more appealing (I'll keep looking some more), do you have SeaSonic or XFX PSU's available?
* By "short lived" I mean failing near the expiration of warranty, about 2 - 3 1/2 years, some earlier. We saw a number of failed CX models reported here a while back, it may have been due to ChannelWell (the actual maker of the CX series) having received a batch of faulty parts or it could've been the use of the lower quality capacitors - I never found out which but still consider it when recommending PSU's and why I went on this rant.