Typically at such low res of 1440 x 900 and with your healthy budget i would hit a nice 23" LCD as well hehe Else a single HD 6850 (with option to CF) would already by overkill IMO Also make the wrong choice in SSD and you'd be dissapointed @@ 32GB even for just boot/OS seems too small but hit a 60GB Sandforce based one?
I'd go with the amd build with some changes.
First I'd get the amd phenom 2 955 with a hyper 212 plus.The difference is minimal as a change of the 955's multiplier makes it a phenom 2 965 and it can be done just by changing a number.As an alternative you could get a phenom 2 x6 1055t which would be more futureproof.
Next for the motherboard,get the asrock 870 extreme 3.It has usb 3 and sata 3 which the mobo you chose lacks.
Change the 6870 model to this as they are the same in terms of performance.
+1 @Batuchka. On that resolution, get a HD6850 at most (a HD5770 would do), or a GTX460 if you care about PhysX. If you're thinking of upgrading your monitor to 1920x1080 any time soon, then a HD6870 OR, get the cheapest HD5770 but plan to sell it along with your old monitor, and wait for HD69xx or whatever high end comes out this month.