(Moving OP's own answer to an Answer:)
so after installing Ubuntu 13.10 and booting up, I did the following :
press ctrl-alt-T or press ctrl-alt-F2 (even if you got blank screen or just see the Ubuntu wallpaper) and enter :
sudo apt-get install compizconfig-settings-manager
note: while in ccsm, disable the unity plugin
Then I enter :
sudo apt-get upate && sudo apt-get install xubuntu-desktop
press ctrl-alt-F2 and login, then enter :
sudo stop lightdm
sudo Xorg -configure
Your computer should now start up with Xubuntu Xfce 4 desktop and having all your Ubuntu apps and data intact eg. firefox or chrome browser history, cookies.
Go to Settings Manager and do configurations eg. session and startup
This posting will be of interest to those who want Ubuntu but whose computer hardware does not support Unity desktop or those who do not like to use the Unity desktop.
Important note : your location affects your download of Ubuntu software, so to be safe, choose a location where you know the servers (will with high probability) have the complete software. Your location is specified when you select Time and Date. Do not trust mirror sites outside the US.