We have a mid '09 13" MBP with 2.5 ghz, 4gb RAM, 256ssd and a mid '09 15" MBP, 2.8ghz, 4gb RAM, 256ssd .... both well spec'd. When doing the same tasks on each notebook, for example sorting through and editing photo's and working into page layouts the 13" MBP seems to have to work so much harder ... fan's a blazing hot as hell, even more so when hooking up to a 24" ACD. Whereas doing the same tasks, same software etc the 15" whether in discreet or integrated mode sails through everything fine, I never hear the fans and it is 'snappier'. I understand the 15" has two fans and the 13" one, could that make such a difference? Surely 2.5 to 2.8ghz can't make much difference in how stressed the machine seems to operate?