Well, nobody can keep you from doing it, but then you're destroying a nice MBP and steal power for some lousy cents/month.

Don't even bother to use your CPU for mining, it's simply not efficient enough. You will pay more for electricity than you will earn from bitcoins. Search the forums.

Paul Kalkbrenner!

Very nice, why not sell high-quality posters in a shop?

I'm using the MSI FX890-GD70 too, with 4x5850, no extenders, in a Coolermaster HAF-X. The 3 bottom cards are overclocked to 900/300, the top one only to 820/300 because of cooling problems... But this way, they run at 74°C (top card), 70°C (2 cards in the middle) and 57°C (bottom card) doing about 1.3GHash/sec. All I did was spacing the cards using some plastic parts and installing one optional 120mm-fan inside the case, blowing directly towards the cards. Power usage is about 670W.

Started 2 days ago, doing around 1.3 GHash/Sec with 4x5850 (not running at full speed yet, have to improve cooling)