you're right, my bad it is the 16" or above that is capable of 1920x1200 and that is all due to the way the LCD is shaped. Why do you want 1920x1200 exactly? why is 1080P full HD not good enough?
the only 15" laptop I could find in recent history that had that resolution was the ASUS M50 series. The problem is they probably won't meet your standards in the CPU/GPU department.
You might be able to fit the
LCD into a barebones machine, but there is no real way to be sure that it interfaces the same.