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#11
Sounds about right. Finding any reviews with a direct comparison between the two is rather difficult, too many generations between them You can however use this one for the GT 430 that has the 9600 GT in it,
ZOTAC GeForce GT 430 1 GB Review - Page 9/32 | techPowerUp
and this one that has both the GT 430 and GT 520,
ZOTAC GeForce GT 520 1 GB Review - Page 9/27 | techPowerUp
and after comparing between the two reviews the 9600 GT is quite a bit faster than the GT 430, and to make it worse the GT 430 is a fair bit faster than the GT 520. One nice thing about using those two reviews is that with the exception of the driver used in each, the rest of the test system hardware is the same (i7 920, motherboard, ram, etc).
How much are you looking to spend, and what is the main use going to be?