X-bit Labs take an indepth look at the Centrino Duo Mobile Platform:

However, there is still one frustrating factor that spoils a little bit this rosy picture. Unfortunately, Intel Core Duo processors have very limited life cycle (and as a result popularity cycle). In the coming fall they will no longer be the latest and greatest mobile processors any more. New dual-core mobiles solutions that are currently known as Merom will be coming out by then. And this fast generations switch has its reasons. The thing is that today's Core Duo processors have one serious drawback: they do not support 64-bit EM64T extensions. Therefore, when the new Microsoft Vista operating system comes out next year, all today's advantages of Core Duo can fade away. Although Vista will support 32-bit as well as 64-bit processors, its will be optimized for more advanced CPUs, of course. So, Core Duo processor owners may be quite disappointed in the long run.