You have a strange obsession with your PC's temperature. So I'm assuming you either:
1. Overclocked
2. Didn't properly set up cooling for your PC
I could leave my PC Folding@home for 6 weeks straight and not worry about it overheating
Edit: Also, there is a pretty large population of PC users that never turn their PC's off (myself included). It's not really a big deal.
Edit2: I wanna make sure you know I'm not attacking you, just curious
I've had a few computers with heating issues, but they were always very much overclocked AND My Thermaltake heatsink fan would usually keep the cool. Thing was as loud as a vacuum cleaner though, the problems arose when I would turn it down so it was quiet, then the heat became an issue.