14 or 15.6 inches?

Hello, usually I know exactly what I want in terms of computer equipment, but right now I'm hesitating terribly... If you could tip the scales one way, it would help me a lot.
I will soon be leaving my family home, I have a relatively powerful desktop computer but I'm not taking it with me, I'm a future student and my parents are convinced that I absolutely need a laptop. I'd love your input!

So it's for student use, I'll be carrying it around, and browsing the internet.
I'm hesitating between these two laptops:
the 15.6 inches http://www.ldlc.com/fiche/PB00120655.html
and the 14 inches http://www.ldlc.com/fiche/PB00130350.html

- The 15.6-inch has a Core i5-2450M, the 14-inch has a Core i3-2370M (for which I couldn't find any reviews.. )
They both have roughly the same frequency and the same number of cores, the only notable difference is the "turbo boost" technology on the Core i5.
I'm used to a Q9550 on my desktop..
Is the difference in power between these two processors not too significant? And compared to my Q9550?

According to the tests I've checked online, the Intel HD3000 graphics chipset can run most games on low settings, do you think it will be possible? Playing Mass Effect from time to time would be nice, even on minimum quality.

In terms of transport, 15.6 or 14 inches is still quite close, does anyone have experience with these two formats to share? And in terms of usage comfort?

Regarding heat, does a 14-inch (since it's denser) heat up more and therefore make more noise than a 15.6-inch?

My heart is torn between these two laptops.
It is ultimately up to me, of course, but... I can't seem to decide..

Thank you!