Xfx hd 7850 1gb

hi, i see the xfx 7850 1gb on sale at newegg for 141.99 do you really need the 2gb version? i am using a i5-2400 with 8bg ram and 700watt extremepower psu, i play mostly bf3 and just ordered warfighter, and planning to get crysis3 right now i have a 550ti any advice ? would like to keep system for a few more years, or should i keep my 550ti for a little longer and then upgrade, it does play bf3 ok for now