!!!

!! RAM
It seems hard to get more that 8GB of RAM for a laptop as 8GB sticks are expensive and many laptops are said not to support more than 4GB sticks.

!! Chipset
To get Sata 3 a new chipset is required (2011, HM67, QM67, QS67)
http://en.wikipedia.org/wiki/List_of_Intel_chipsets#Core_i_Series_Mobile_chipsets
The QM67 seems to be used in the new Latitude E6320, E6420 and E6520 which differ essentially by the size of the screen.

!! SSD
Modern SSD drives can do 500MB/s and 60k IO per second.
* [OCZ Vertex 3 review|http://www.storagereview.com/ocz_vertex_3_max_iops_ssd_review_240gb]