(update: this version is slower, show more detail and includes a song from Coldplay to liven things up a little).
Our early 2008 model MacBook Pro was on it's last leg. It was extremely slow, unresponsive, and I was prepared to buy a new MacBook Air. As a last ditch effort, I decided to upgrade the RAM (to 4GB instead of 2GB) and I purchased a new 5400 RPM Hitachi 500 GB hard drive to replace my old one, which was failing. I took the new hard drive and made a clone of my existing drive via a firewire enclosure. I booted from the newly cloned drive to confirm the process worked and all the data had transfered. I took out the old drive, installed the new one and voila, like-new computer! Thanks to ifixit.com for the new drive, the tools, and the user guide.