the rest of your build looks good.
i suggested that psu because of the case you had picked; that antec 850w is a different, a bit larger psu form factor, cpx, which is currently only supported by 3 of antec's cases, p183, p193 and 1200.
and for the money it's a great deal, it just doesn't fit too many cases bit it does fit the one you picked, and the combo deal just makes it better.
and it's not a crap psu (if that's what you're thinking) by any means, here's a review.
JonnyGURU - Antec CP-850 850W