MACs aren't that bad. We have an iMac, a Power G5, and a powerbook. At some point or another I have replaced memory or added parts. The power book we recently put a larger hard drive in and it didn't take me 6hrs
The ONLY thing I hate about MACs is that I can't get them and my PCs to use the level of Wireless encryption I want them to on my network. So I tell Leah she's SOL and has to connect hardwired when she wants to access the network.
Back to the laptop thing... my brother once had an overheating laptop. He took it all apart and then reassembled it in a concotion of plexi-glass and other plastics with tons of holes and vents. Of course he's an uber geek and did it more for looks than anything I'll see if I can dig up a picture of this thing.
I use one of those cooling pads someone posted a SS of. It works well on my laptops.