reinstall Kubuntu 12.04

I had Kubuntu 9.10 installed in my computer for a long time. Recently  I want to update to the newer version. But it  seems not possible to upgrade from 9.10 to 12.04. So I decided to reinstall the system. Kubuntu 12.04 is selected because it is a stable version compared to 12.12 and it works for 5 years.

A summary of my computer and the list of partitions:
0) I have 1T total disk drive
1) I have 300 G of data files in the /home/ which is in the partition /dev/sda1
2) I have 8 G for swap
3) the current /dev/sda1 includes the root /, boot (/boot), and home (/home); and the /home is in the same partition as root. The sda1 takes 800 G, but only 300G used.

Before doing anything, I backup everything in the /home directory to an external hard drive.

Then I use the partition tool in my existing linux system to reduce the sda1 from 800 G to 400 G.

Then I burned the Kubuntu 12.04 image to a DVD reader (only writable for once) which is cheap. I tried the usb installation, but it not easy and not working well.

I decide to install the Kubuntu in the new partition than in sda1, so that later I can copy all the old home files to the new partition/installation. Afterwards I can remove the old partition and combine it with the new one.

I decide to delete the old swap and then make 3 new partitions:
1) /:  20G
2) swap: 8G
3) /home: the rest unused space

Then I started the installation by inserting the dvd into the computer.
1) I keep the old partition sda1, but do not use it
2) create new partition sda2 in the ext4 type for the root / (primary), because the kubuntu 12.04 recommend the ext4. I choose to format this partition.
3) create a new partition sda4 (primary) in the ext4 type for /home, so that if nexetime I need update/reinstall the system, I will not need to modify the /home. I choose to format this partition
4) create a new partition sda5  for swap(logical)
5) I choose the /dev/sda  as the boot loader
6) then click on 'install'
7) choose the lanuangue, timezone, keyboard layout.

About 15 minutes later the installation is finished. I restarted the system, and created the user names as before.

When I log in, in the file system, I can see that:
1) 500 G for the new root and home using Kubuntu 12.04
2) old installation 400 G
3) swap

Now I copy the old home files to the new home file.

After copying all the old home files, I decide to reformat the old sda1 partition and combine it with the new one (at the same time, leaving a few GB free as extended ).