Once a user logs on for the first time on their account, they customize theme

Once a user logs on for the first time on their own session, a window will appear that will ask them what they want their theme to be, background, etc. This would be a great way for the end user to customize their desktop off the bat.
Example:
-Bill installs Ubuntu on the live-CD; after restart and login, a window appears using the default theme and asks his background he would like, along with icon theme and other theme settings. After he has customized his desktop he needs to create a user for his daughter. Once she logs on her account she picks her settings and has a different desktop that is distinguishable from her fathers