Yes, you are right about using just 1 stick of RAM but I thought I would do this build from the feedback I have had from other users and the problems they have encountered to see if I ran into the same problems. I didn't.
The reason I did the initial build with one CPU and then swapped it over was to show how to upgrade a CPU and also how to change the stock cooler for a 3rd party one, as this is what a lot of users tend to do.
I also ran through setting up the OS in IDE, AHCI and RAID mode which I wouldn't normally do. Again, this was so I could see how the motherboard handled each of the different configurations and also, so I could offer practical advice if question came up rather than having to reconfigure things later on.