If you usually just do the documentary work and web surfing, and sometimes 3D gaming, I will recommand you to buy R7500.

But how to choose from Original ATI and thirdparty? I think it will depend on how good your monitor is.
If you have a 17" monitor, it is ok to choose the third party R7500 (and it is cheaper)
If you have any monitors that is larger than 17", you might want to choose build by ATI R7500 'cause of the 2D quility.

If you want to save a little bit money, thirdparty ATI card will be a better choose, otherwise you don't have to save 10~20 dollars to get a costdown graph card