Does your case really have bad airflow, or is it just bad wire management? If you add a few fans strategically placed near vents (or even open pci slots) you can improve your airflow greatly. Check to ensure that the heatsink is seated properly, and be sure not to use too much thermal compound.
I'm totally in the same boat as you ^. I think that the evolution of technology has far surpassed that of most consumer/enthusiasts' actual computational needs, while computers are now veering more and more into the supercomputer class.