Going from 2 cores @ 2.4Ghz to 4 cores @ 1.6Ghz doesn't seem like a major upgrade.
In what way does your current CPU not support your workloads?
Graphic softwares and specific data analysis softwares like SPIP take certain time to respond. Some games, may overload the CPU leading to overheating. Unfortunately, my laptop warranty expired. in the future I will buy an upgradable laptop
Some games, may overload the CPU leading to overheating.
Cleaning the cooling/fan system should fix that.
I'm not sure a i7 CPU upgrade would do much good for you. Have you looked at the price of a Core i7-720QM CPU?