Judi,
The main problem with my laptop (7 year old Compaq) is that it will only run on power now as the battery failed and can't recharge. It was my daughter's laptop so was pretty well used before it was handed down to me. The other problem is overheating. Overheating seems a common problem but on mine it's worse when running the dvd drive too long. Helps to transfer things over onto the actual computer to watch.

I am a bit like mrsD in that I liked my old tower. I particularly liked that I could open it up and clean it out and replace parts myself.

The "chill plate" for a laptop sounds like a great idea.

My daughter's MacBook overheats as well but it's kept very busy. It had a problem with the white rubber underneath the keyboard. Will post details below in case someone else has the same problem.

http://www.apple.com/au/support/macbook-bottomcase/