Will this run Diablo 3

are we talking about your desktop or your friend's laptop that you claim runs skyrim on high with 6520G?

I don't have trouble believing that your GT450 can run skyrim at 1080p as it's a desktop card. 6520G is an integrated GPU which is on the same die with a LAPTOP CPU, so do the math on how much the performance falls off...

PS> please learn to use the edit feature

Here's a video of it running on high/med with various adjustments

Apologies on not editing. I always seem to forget that feature. Anyhow, I was speaking about my friend's laptop. I'm not saying he is running it with the same settings I use but he does run the texture quality on high, the other settings he tinkered with. He also runs mods on top of this so I'm not making this stuff up just for this person's benefit. I've actually seen it run and it ran fairly smooth from me looking over his shoulder while he played. There is one thing my friend's HP has more of and that is the amount of ram. He has 6 gigs of ram and not 4 but the rest of the specs are the same.
so in other words, it's a completely different laptop and you're not even sure about the settings your friend is running on, yet you choose to relate that information as a qualification how a completely different laptop would run the game. ohh wait, no, completely different game. Sorry, but that's just ignorant and inappropriate.