On my ThinkPad, I use either Norton Ghost or Acronis True Image to clone the hard drive. This takes less than two hours. Then I swap the drives and run the laptop off of the copy. To me there are two advantages:

1. I know for sure that my backup is bootable.
2. I know that if the drive in the laptop fails, I can insert the other drive and boot without any recovery process.

The downside is that 80Gb laptop drives are quite expensive.