I close the vents in my room during the winter. If it's cold, I turn on all three monitors for about 10 minutes, then take off my shirt and open the windows.
I actually opened my windows and started a current through ym room with fans in the windows at opposite ends of the room. Put on a jacket and gloves, was very hard to type.
Cpus were 15-17 C under full seti load. Room was much cooler.
I've not OC'd them lately, it's been to freaking hot in here lately. hell, half the time I don't even run both computers, the eMachine stays off usually now, and the Celerons stay at 400. They'll be fine, I've never seen them higher than 50, but life becomes unbearable in here right about there.
Using your computer to heat a small area, like an appartment, or a small computer store is actually much cheaper than gas!