Well, Download ATI drivers from [URL] link and don’t forget to read Installer Instructions in the same page mentioned. Guide also show how to install in Red Hat Linux and remember to go through the minimum system requirement (Kernel, Xorg).  The above mentioned link downloads ATI Radeon HD 4550 series which could be clouser to our GPU. ... Hope this info is enough :-)  
I have got a Studio 1555 with VGA card of ATI Mobility Radeaon HD 4570, and i have installed a Linux 64 bit on this laptop, can you guide me how i can install my VGA drivers?
I have installed Linux 64 bit on Studio 1555, can i install the ATI Mobility 
Radeaon HD 4570 VGA card as well?