The value of DDR3 has been discussed at length and it's widely believed that the actual performance benefit of DDR3 is negligable at this point in time. The higher latency of current DDR3 memory tends to counteract the benefits of it's higher bandwidth.

It is important to note that, at this time, HDX notebooks being shipped with DDR2 use a different motherboard than those that come from the factory with DDR3 and cannot be upgraded to DDR3. If this is an important distinction then it is recommended that you configure your notebook with DDR3 during the initial purchase.