Ahhhh, my 100th post :)
I upgraded my MacBook to Leopard last night, here's what I did :
1. Wait until Leopard's first update.
2. Backup my Installer CD to a DMG file using Disk Utility, put the disc away in a safe place.
3. Set up an external HD with two partitions, one of about 8 GIG for the installer, the other large enough for a backup of my MacBook.
4. Restore the Installer DMG to the 8 GIG partition using Disk Utility and verify it.
5. Boot from the new Installer partition.
6. From the installer, switch to Disk Utility, repair the MacBook's disk.
7. Restore the MacBook's disk to the large partition on the external drive and verify it.
8. Check the backup boots OK. (Or, AT LEAST check it comes up in the Startup Disk panel!!)
9. Perform the actuall install, I chose to do an "Archive and Install". It worked fine !!