My Lenovo 3000 N100 work laptop always had a noisy fan but over the past couple of days, its been pretty noisy and the overheating causes my laptop to turn off.
I got the tech support guy to give me a replacement, so he checked the inventory and they had another slightly-used Lenovo 300 N100. After swapping hard disks which was pretty simple, I wanted the 2x512MB RAM replaced with the 1x1GB, 1x512MB RAM from my former laptop so things went quite well till I discovered the "k" key on the keyboard wasn't working.
Then, we decided to get the hard drive and RAM back to the laptop that I started off with and transplant the cooling fan. There was a tiny connector on the motherboard for the fan along with a couple of screws - they have a case panel to replace the fan too! There was a pretty big gang of dust bunnies covering the air vent, preventing air flow - no wonder it was overheating! After getting rid of the dust, transplanting the new fan in place and getting the case closed, I'm back in business.