and what about ATI Mobility FireGL V5200 graphics controller with 256 MB??
The ATi FireGL V5200 is based on the X1600 core, I would say it's more powerful than the vanilla 6600. It's a more up-to-date card than either the 6600 or X300, with a full feature set so it'd be a good choice. Though in its FireGL guise, it's going to cost you significantly more than a regular non-OpenGL optimized graphics card.
Well price doesn't really matter, I need to test a new laptop for the job so they will pay for it