it's no point waiting with buying hardware for windows 8.
it will be compatible anyway, upgrade from 7 to 8pro will be cheap as chips if you'll ever decide to go for it.
intel released ivy bridge not so long ago (i've got my 3770K from one of the first retailers in UK who has had them in stock) and i can say that even sandy bridge is all you need. (there is a few advantages of ivy tho - like sata3 and pci-e2).
another major update will be ivy extreme -more cores, higher clocks (which is extreme - pretty much only for oc maniacs), and then another year (at least) for new manufacturing process.
current cpu's like 2600K, 3770K (or even non-K versions, if you don't plan to overclock) are more than enough for photo editing.
i am working on RAW from Nikon D7000, so already quite big files, and can't see any space for improvement on my computer
(mentioned 3770K, 16GB 1866MHz Ram, ssd for system and raid-strip for storage, still without any gfx card till next month, currently working on hd4000 which is built-in in my cpu)
gpu-wise geforce gtx 670 is the way to go (oc'd versions like gigabyte windforce can perform better than stock 680's with still significant difference in price)
prices of ssd went down massively (ocz agility 3 is well performing budget solution), for data storage, swap, cache etc go for raid on 'oldschool' hdd (strip)
reassuming - if only you don't have D800 (36MPix is great, but omfg 100MB RAW files) or hasselblad-like stuff, you'll be more than happy of current intel cpu's, you don't even need top graphics card - this is ONLY for gaming. 8GB of good fast memory is more than enough. ssd + stripped hdd's. just don't ever think about saving on motherboard, psu and case!
mobo is good to get 'gamers grade' like for example asus ROG or Sabertooth series.
case - big, spacious and well designed inside. one of the best which isn't too expensive is CoolerMaster HAF X. I can suggest few more good cases in different price ranges.
psu - it feeds all your components with power. has to be reliable.
screen - as good as you can afford.
for what i'm doing LG IPS235 is enough.
if you can afford EIZO, go for it. so far best screens for any job that requires good color reproduction.
...but built-in calibrator is 'spare gadget' which imo is way too expensive, you can get spyder4 or colormunki and calibrate virtually everything around you. they are industry's leading solutions and are relatively cheap.
any more questions - i'm more than happy to help