Watch out for that - recovering from testicular cancer, one of my thoughts was "I wonder if constantly using a laptop contributed". I know make sure to use a tray or a table whenever possible. Laptops are designed to push much of their heat down, into your lap. That can't be healthy.
Alun> Sorry to hear that
I once had to test a fujitsu seimens 'Celcius' laptop. A school teacher had complained that it had taken the varnish off his kitchen table. It got to 55 degrees C. FS said the case was the heat sink and it was a 'desktop replacement' and not designed for a lap. How odd that it looked like a laptop.