Hard Drive: I would instead go for
http://www.newegg.com/Product/Product.aspx?Item=N82E16822152185 instead.
Twice the capacity of the WD drive and you get extra performance, whilst paying less.
PSU: Mine would still work perfectly fine. Though both are excellent units, I would take the Antec, simply because you are saving $15 in doing so.
GPU: There is not enough between the two cards to say one is better than the other. Both are as near as makes no difference on par, and swap blows for which performs better on different applications and different games, but the difference is never more than 1 or 2 fps, so just go with the cheaper option, which in this case is the 560 before MIR, but the 6870 after MIR.
I would, however, swap to this 6870:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814150506
because of the better warranty and much lower price (which is apparently just for the weekend, so if you aren't ordering today, then go for whichever the cheapest 6870 is at the time, but I would recommend against PowerColor). They are the exact same cards, just different manufacturers,