GPUs for Single or Multimonitor setups

[AhSoul]

Currently running a GTX560oc at 1680x1050 (with 2nd 1680x1050 screen for MFDS etc).

 

At some point I want to either:

 

a) get a nice big single monitor (1900x1200 or something) or

b) go the whole hog and get 3 screens side-by-side (I guess these wouldn't need to be quite so high a res as a))

 

Is there a base GPU I'd need for either situation?

 

I've been offered a 7870 2Gb ghost edition but don't know if that's good enough for a) or b) or neither.

 

I'd like to be able to run a high level of detail with a decent framerate (kinda obvious I guess). Currently I get 30-45 with most things on high.

 

Other specs are i5 3470 3.20GHz, 8Gb ram, 120gb SSD.

 

Thanks for the advice!