I am normally a huge ATI Radeon supporter.. but in the case of the "mobility" GPUs, I find that nvidia generally has better bang for the buck.
ATI's mobility offerings are... cheap. and I dont mean inexpensive.. I mean cheap.
Powdered macaroni n cheese cheap..
Ramen noodles cheap..
I think I've made my point..
I see from the specs you posted, you're thinking of getting a laptop. Im not sure if you've been told or not, but a desktop the same price as a laptop will, in most cases, net you a -huge- performance advantage. and even desktops with similar specs tend to perform better than their laptop counterpart..
Most (if not -all) Laptop GPUs and CPUs are designed to be power efficient..
Not fast.. You sacrifice speed for portability.
Granted, these days, the trade-off is less pronounced on some of the higher end laptop and desktops.. But the low end systems still vary by a bit.
Hope this helps.
*edited to fix a missing d heh*