Dell will keep Alienware as a separate company, they know thier "Gaming" systems suck compared to all others, and I think they will keep Alienware as is, a high end gaming company using the latest and greatest parts, water and air cooling systems and notebooks, ditch the XPS series, and recomend Alienware.
I think this is a stab at Intel as well, being able to sell AMD processors under the Alienware name without loosing the backscratching from Intel on chip prices when "Dell" only sells Intel. "Dell" will continue to sell only Intel, but I bet we see even more, if not all, AMD based Alienware sysems from now on.