nothing a future proof... especially not a budget build. I see you are still under 400, try upgrading to a radeon 7770. will do a lot better in games (if thats what you are building this for) then upgrade the cpu in the future.
Not true at all, Intel change sockets far more regularly than AMD. For the FM2 socket in particular, AMD are commited to it for another generation after Trinity.
It depends how much you want to upgrade really. FM2 is never going to be good for a high end gaming system but it is excellent for low end and viable for mid range. That A10 should be able to handle something like a HD 7850 if you ever plan to upgrade to something like that.
I realize I went like 17 dollars over, but you could save up 17 bucks extra and it would really be worth it. I built this trying to focus on having a phenom ii x4 and a hd 7770.
35 over budget but really worth it
A8 5600k over a10 5800k since you won't be using crossfire (also using a 7770 so no issue with crossfire not scaling)
A8 5600k over performs the IIx4 and is only 200mhz slower than the a10 (OC the differenece)
750GB WD for same price as 500GB seagate
Its worth it to save the extra money up and grab this rather than settling for something weaker.
Swaps out the 7770 for the 7770 to stay in budget
This performs about the same as a10+6670 but no issues with scaling corssfire.