What laptop should i buy

Hi everyone,

I have got a desktop computer but am moving country and cannot take it with me so its time for a laptop. My budget is 650 pounds.

I have researched a lot and found a couple of i7 laptops with 6gb of RAM that look good. However these have shared graphics memory.
I have found a couple with i5 cpu's and 6gb of RAM and these have 1gb dedicated graphics.

I want the laptop to run software like adobe premire pro and after effects. also for casual gaming like COD modern warfare 1. (very old games)

What i have to decide is wether i want a better cpu with shared graphics or a worse cpu with dedicated graphics.

I also wonder if because the i7 is 8 cores instead of 4 like the i5 it would be a better choice.

The other thing is i think that the i7 is 1st generation whereas the i5 is second. What is the difference and how does it improve it.

And they talk about max speed of 2.9 ghz with turboboost. Will i be able to increase it to this speed and why dont they just have it on that speed in the first place. is it more likely to overheat and stuff?

Please answer quick

Alex