Standard

Upgrade
Export Registry to landing zone – obviously off this box if it is to be reformatted
Export settings to landing Zone
Run Diags and detach Database
Save DB files to new landing zone
Format and update to latest service packs
Name the machine the same thing – be sure to remove computer from AD and let it re add it.
Do Simple Full install
When console opens
Close Console, do not start service
Standard
                Import Registry
                In diags, Detach db files and move to subdir
                Move old db files from landing zone to \Database Directory

In diags, Attach Database