SPEC benchmarks for Graphics

[shadab_khatib]

Hello
I am about to purchase a mid-end graphics card for my android game development and and to learn 3D modelling applications. And in future might be using for OpenGl programming purposes.
I am in a fix that which among the three I should consider Nvidia GTX 560,Nvidia Quadro 600, ATI AMD HD 6850
Basically I would like to enter the field of Graphics (Game Development),and App Development.
I am in a fix about deciding which graphics card to purchase wheather a Professional Card or a Gaming High End Card.
If I would like to run the applications such as Autodesk (Inventor, Maya,3DsMax), Catia, and other game devlopment engines to develop and generate 3D content then what are the main specifications should I be looking for in the graphics card "technically".
How can I know a graphics card's performance for OpenGl development(if possible with some rating or measurement or any possible explaination).
Should I be looking out for the SPEC rating of the graphics cards. If yes , If then please provide me a link to lookout for the SPEC rating of it.
If no, then please describe what should I be really concentrating on?

I am just a Computer Science Engineering Student beginning to learn graphics manipulation and generating them, and not a professional.
Answer in depth, because it is a big investment I am looking forward to put in the graphics card.

My current Hardware Configuration is
Processor :Intel Q8200 2.33ghz,
Motherboard : Intel DG43RK
RAM :8GB (DDR3-1066Mhz)
Graphics Card:NIL
Monitor : Dell SP2220M Full HD LED(1920X1080)