Fan driving me nuts

Hey guys I have a MBP 15" with Snow Leopard, originally had Leopard on it. Now the fan on this laptop is driving me somewhat insane. Looking at the Activity monitor I can see that kernal_task takes up 55 threads. Having said that iStat Pro reports that my CPU is at 78 degree's, now for me thats worrying, because I dont really use the laptop for intensive stuff, unless im playing Football Manager. I have it sat on a hard surface. This also happens when the laptop is idle.

I found that when my MBP started cranking up the Fans a peek in the activity monitor showed Mail causing a heavy demand on Processor hence fans. Never did find out why Mail did it, but quitting Mail and re opening sorted it until next time, which was very infrequent. Or if it continues resetting the SMC might be an option.

Think I will power off reset SMC, and power on again when I have finished my dinner.

Well that didn't help, any other way that I can track down whats causing this? The fan wouldn't be on its way out would it?

Posted about this on another forum that I frequent and someone suggested that it might be due to dust. But I cant do anything about it as taking the bottom off would invalidate the warranty.

kernel_task taking that thread count is normal. Sort activity monitor by %CPU and see if anything is hogging the CPU.

can of compressed air is always handy - blow around the keyboard and around the hinge. And definitely check Activity Monitor/CPU when it's running the fans hard to check what's eating up cycles.

found that it was the printer software causing the issue. Removed it and now everything's back to normal.