I am using an ATI Mobility Radeon HD 4570 with 512MB of memory. Whilst being disappointed with Dell for the updated graphic driver, I told myself that I would have to do something which Dell would not have done.
In fact, I've managed to download the latest ATI driver for their desktop HD 4550 series graphics card and then use Mobility Modder software to modify the desktop ATI graphics driver so that I can install it on my laptop.
For your information, the firmware which Dell has listed it on their website was based on Catalyst 9.8. Well, there's Catalyst 9.12 right now, ready to be installed on all desktops which use the ATI graphics card. I don't see why I should be using a crippled driver from Dell!
Nevertheless, I've managed to install the Catalyst 9.12 firmware and it has increased my laptop experience! I could play Street Fighter IV in a smoother way and I like it!
I would recommend people to use desktop graphics driver if they are running on an ATI chipset. You will be able to use desktop drivers once you have modify the firmware. Besides, with the updated 9.12 firmware, my laptop is now running on Direct X 11!!! Excellent!