Nautilus does not support this functionality. What you might want to do is use session saving, or write a script to have nautilus open those directories by default.
You could replace nautilus with this script in your start up applications. (I will need more time for the script part).
Unfortunately, some folders have to have certain owners and permissions to make Ubuntu work. You can, however, just run the file browser as root. In Xubuntu, the file browser is thunar. So, running sudo thunar will let you do anything in the file browser as root.
If you want a way to run Thunar as root without typing anything, you can go to /usr/share/applications and open thunar.desktop with Gedit. Edit the Exec=... to read Exec=sudo .... You're going to have to run Thunar as root to edit this file. After saving it, make a link to it on the desktop, and you'll have your file browser running as root. You can even pin it to the launcher. If you need help with anything comment.
Be warned: Running Thunar as root is very dangerous. Use it with caution.
Best Answer
You can do that in many ways:
Log in as root
Open nautilus as a root
You can add "Open as administrator" as an extension to your right click:
Download the nautilus-gksu package for your architecture from either of these 2 locations, and save it in your downloads folder.
32 bit: Direct link from ubuntu.mirror.cambrium.nl
64 bit: Direct link from ubuntu.mirror.cambrium.nl
On your 64 bit install downloaded nautilus-gksu_2.0.2-5ubuntu2_amd64.deb & extracted right in your Downloads folder
On your 32 bit install downloaded nautilus-gksu_2.0.2-5ubuntu2_i386.deb & again extracted in Downloads folder so terminal command