Dell Fan Weirdness 
Something weird happened about a month ago.
I downloaded and was running this CPU speed app (IK8FanGUI) which also let you watch the temperature of the CPU and the activity that the fans were doing. I had it set on "watch values only", and what would happen was that after some period of time the fan would come on high and stay on, the CPU temperature would stay around 38 or so, and the CPU speed would stay locked at the slowest setting (~600MHz).
This fan speed made the computer annoying to use, while the slow CPU speed made it useless to use.
A reboot cleared the problem.
Since then I've run the app with a temperature profile, and the fan behavior has been much better. The fan comes on low at a particular temperature range, and on high at a different one. And it all appears to work more or less.
However today I've restarted the computer without the app, and while the computer feels warmer, it also feels faster and quieter. I guess the moral of the story is don't break something that doesn't need it?