Other than that the 520 is DirectX 11 and lower power requirements, it has nothing else over the 9600 GT and in fact is a step backwards,
Video Card Comparison - GPUReview.com
You would be replacing what was a mid-range card with what is for all intents and purposes a low end card, albeit current gen.
If not for gaming, what is wrong with your current card? It still has full/current Windows 7 support from Nvidia for
drivers.