Install Sun Java Runtime (JRE) 1.6.0 on ubuntu

Add to your repository, for Edgy:

deb http://download.tuxfamily.org/3v1deb edgy 3v1n0
#deb-src http://download.tuxfamily.org/3v1deb edgy 3v1n0

GPG Key Information, if yo wish to add do:

wget http://3v1n0.tuxfamily.org/EDD1E155.gpg -O- | sudo apt-key add -

For Dapper:

deb http://download.tuxfamily.org/3v1deb dapper 3v1n0
#deb-src http://download.tuxfamily.org/3v1deb dapper 3v1n0

Now continue:

sudo apt-get update
sudo apt-get install make-jpkg-mustang
sudo make-jpkg-mustang

When all is done check your active java-version with:

sudo update-alternatives –config java

Switch between Ubuntu, KUbuntu, Edubuntu, and XUbuntu

I found some good information about converting between different ubuntu desktops.

1- Install ubuntu desktop from kubuntu:

sudo apt-get install ubuntu-dektop

When it asks what dm to use; kdm or gdm; select gdm… continue…
When done its time to remove the Kubuntu packages;

sudo apt-get remove kubuntu-desktop kubuntu-artwork-usplash

It wil remove some of the Kubuntu packages and with autoremove the rest of the Kubuntu packages kan be removed now;

sudo apt-get autoremove

When done reboot (or restart x) and you have your Ubuntu ready for usage.

2- Replace Kubuntu with Xubuntu;

sudo apt-get install xubuntu-desktop
Select gdm as dm
Remove Kubuntu as explained earlier

3- Replace Kubuntu with Edubuntu:

sudo apt-get install edubuntu-desktop
Select gdm as dm
Remove Kubuntu as explained earlier

4- If you wish to keep the Kubuntu packages simply skip the remove step.
If you wish to revert from Ubuntu to Kubuntu ;

sudo apt-get install kubuntu-desktop
Select kdm as dm
sudo apt-get remove ubuntu-desktop
sudo apt-get autoremove

5- Ubuntu to Xubuntu:

sudo apt-get install xubuntu-desktop
sudo apt-get remove ubuntu desktop
sudo apt-get autoremove

6- Ubuntu to Edubuntu:

sudo apt-get install edubuntu-desktop
sudo apt-get remove ubuntu desktop
sudo apt-get autoremove

7- If you revert to Kubuntu make sure to select kdm as dm, all others require gdm.
Removal of Xubuntu:

sudo apt-get remove xubuntu-desktop xubuntu-artwork-usplash
sudo apt-get autoremove

8- Removal of Edubuntu:

sudo apt-get remove edubuntu edubuntu-artwork-usplash
sudo apt-get autoremove

9- Want to switch from gdm to kdm or vice versa while having both installed?

sudo dpkg-reconfigure gdm
and select your preferred dm
or
sudo dpkg-reconfigure kdm
and select your preferred dm