ASUS 8800GTS 320MB is it good dedicate for Nvidia PhysX

If you already one it or could land one for around $40-50 while having a decent cpu and psu then go for it. In mafia 2 it can make a big difference.

GTX 460 1GB + 8800gt.

I don't have any idea to change my GTX460 now, if i use ASUS 8800GTS for physx is it make any difference? performance wise?

Yes it's a fine PhysX card but a little on the power hungry side compared to other newer cards of equal performance.

It will definitely make a difference in PhysX accelerated games. All... 12 of them.

In mafia 2 expect 15-25% load on the dedicated card while some areas are more intense. Just having the card there so long your cpu is good will give a nice boost in that game while others are different. For me that 8800gt was worth every penny and it beats paying $90 for a GT240 or $70 for a GT430.

Mr.wolfram23 what you mean by power hungry? is it needs lot of power? i have ASUS 750W PSU?

The G80 was never known to be efficient and often is a power hog. Heat is another downside while they often had caps that would easily break off if mishandled.