Hd 4850 vs gts 250

[sid30994]

Hello,
im buying a gpu and id like to know which is better HD4850 or GTS250.
Current Rig:-
E4500@2.6GHz
DG33FB
19"1440x900
4GB Ram
450watt PSU

I'd also like to know for how many years i can game on this GPU(for like all high settings) and i am getting the 4850 cheaper than GTS

 

[sid30994]

i also want to mention that ill be buying XFX versions of these and the 4850 is the XXX edition and GTS 250 is standard edition