GPU for 3d softwares

Hi,
I have,

Processor : AMD FX 6100
[http://products.amd.com/en-us/DesktopCPUDetail.aspx?id=...]
Mtb : M5A97
[http://in.asus.com/Motherboards/AMD_AM3Plus/M5A97/]
PSU :Coolermaster "Thunder 500W"
[http://www.coolermaster.in/product.php?product_id=6735]
Cabinet : Elite 371 (USB 3.0 version)
[http://www.coolermaster.in/product.php?product_id=6720&...]

I work in 3ds max , maya , real flow , sometimes in editing softwares(e.g.,After effect,premiere).
Mostly architectural modeling & rendering(V-Ray,mental ray).

I am looking for the "Graphics card" & "RAM" , best for my work , & suitable for my PC configuration.
Please , please , solve my problem ASAP , I am in hurry .


Thanks........!