I want to purchase a laptop workstation but am confused between the Dell M4800 and the HP Zbook 15. My main need is for trading in the financial market but will also be doing some graphic designing work. I will be attaching two extra 24 inch monitors to it. My desired configuration is Processor i7, RAM at least 16GB and good graphics card (I do not have much idea about graphic card models). I will need it to run 12-15 hrs at a stretch. What do you suggest?