How much of a performance bump might I get from this switch/upgrade

I'm thinking of upgrading from the HP in my sig (turion II 2.3ghz, 4gb RAM, 1gb radeon mobility 4650) to this HP:

HP Pavilion DV6-3050us 2GHz Phenom II X4 N930 Laptop w/$50.00 Mail-In Rebate | Overstock.com

which I can get used and in good condition for about 350. Add to that 150$ that I should be able to get for the one I have now and we're talking about a CPU upgrade from 2 to 4 cores and GPU upgrade to the next series' equivalent (that can share 1gb on top of the 1gb dedicated) for around 200. I want to hold off on going all out on a new computer until a few years into the next home-console cycle. Besides, I can still run most of the most current games at med settings at pretty decent framerates on my current HP.

My question mainly concerns the CPU. Roughly how much of a bump in performance will I see from the extra CPU cores and will the lower clock speed cores of the phenom II under-perform the cores of the Turion II? My knowledge of current gen hardware is pretty basic (if that), but I do know that having double CPU cores doesn't mean everything runs twice a fast, and I also know that running at a lower clockspeed per core doesn't mean that a slower core can't out-perform a faster one on single threads.

 

Just found out this laptop also has an integrated radeon 4250

 

The best way I can tell you is that the upgrade would be double in performance wise all around on that rig. Now if it has the 5650 still in it it will perform better than the turion still but if not than that 4200 is going to be the down fall of that rig all cpu no gpu essentially. basically to think of it you are upgrading never the less it will perform twice what the old one does.

 

It has both gpus. From what i've read, it uses the 4250 when it's in power-saving mode.