Install KDE on Ubuntu

sudo apt-get install kde-standard

Install Xubuntu over Ubuntu

sudo apt-get install xubuntu-desktop

Install sun/oracle java via ppa

Sun (Oracle) java JDK can be installed via PPA now:

sudo apt-add-repository ppa:flexiondotorg/java
sudo apt-get update
sudo apt-get install sun-java6-jre sun-java6-plugin

or

sudo add-apt-repository ppa:eugenesan/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

Icon themes

Faenza Icon theme:

sudo add-apt-repository ppa:tiheum/equinox
sudo apt-get update
sudo apt-get install faenza-icon-theme

Faience Icon theme:

sudo apt-add-repository ppa:suraia/ppa
sudo apt-get update
sudo apt-get install faience

Elementary Icon theme:

sudo add-apt-repository ppa:elementaryart/elementarydesktop
sudo apt-get update
sudo apt-get install elementary-icon-theme

Installing Tweak

sudo add-apt-repository ppa:tualatrix/ppa
sudo apt-get update
sudo apt-get install ubuntu-tweak

ili

sudo apt-get install gnome-tweak-tool

Forcing ACPI for power off

Problem: Ubuntu 12.04 and machine wont power off
My machine is Dell Latitude D630 with NVIDIA Quadro NVS 135M

1. sudo gedit /etc/default/grub
2. Find where it says, GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
3. Change this to GRUB_CMDLINE_LINUX_DEFAULT="quiet splash acpi=force"
4. sudo update-grub