Is there a main performance between 7600 GT and 7900 GS

i'm running this years game at frames between 20 and 30 when everything maxed out. and i have this: http://www.hs.com.tr/index.cfm?fuseaction=objects2.detail_product 7600 GT

if i buy this: http://www.hs.com.tr/index.cfm?fuseaction=objects2.detail_product 7900 gs

will my fps at games for example get to 40-50 instead of 20-30 ?

You'll just be wasting your money if you go from 7600GT to 7900GS,if anything,wait for the 8800GT and HD 2900GT,those will be MUCH better upgrades from a 7600GT.Indestructible2