I have an AMD 2800+, just slightly overclocked to 2.5 Gh. It has an excellent heat sink/fan setup, but you sure can't touch it - and that's nothing compared to my new graphics card, an ATI 800XL!
Most of the newest intel chips run so hot they fry unless water cooled!
On the other hand, my '030 A1200 run very cool. With 128Mb of RAM, the CPU is only warm to the touch.
The '040 is the hottest Motorola CPU (at any speed) - I couldn't even run an '040 in my desktop A1200. It was way to hot, and a fan would not fit in there.