upgrade or buy a new pc?

[theproffesor]

Hi guys I 'm new in digit
And my prob is I have a 2 year old pc:
X2 555@3.8ghz(can't unlock )
Msi 785gm p45
4 gb ddr3@1333
I ball cabinet with 250w
Nvidia gt430
500gb
Display 1920x1200@60hz
I know this rig sucks I play my games at 1024x768@low very bad experience
I was a noob, so my cousin bought this for me...
I have 18k in my pocket and I was thinking of buy this
Sapphire hd7850 oc@15k
And seasonic eco 600w @4.3k(Flipkart. Com )
But I'm confused that it will bottleneck??
But a second thought crossed my mind because crysis 3 is coming on feb So I Thoough i should wait. Till then and save some cash and I could, probably 50k total and buy this:
I5 2500k@12k(I know about 3570k but I'm gonna oc so I can buy cm hyper evo212+ frm. The saved money ,)
Asrock z77 extreme 4@10.6k
G.skil ripjawsx 8gb(2*4gb)@3.4k
case: cooler master elite431@3k(not sure)
Mouse:Logitech g300@1.2k
Display : reuse my old lg 1920*1200
Hdd:Seagate. 1tb@4.5k
Psu:seasonic eco600 600w@4.3k
Total :45k
So I cud buy a hd7870@20k(5k more)
What do you think guyz I'm going back and forth with my idea, sorry for bad English as I'm typing in a 2.8" screen (f**k)