when to resize partitions

[Stephen Constantinou]

Dear All

I have a PC with a 160 GB HDD.  It is partitioned as follows

            SIZE      USED
sda1 fat16    41MB    33MB
sda2 ntfs  78279MB 56634MB
sda4 fat32  3380MB  2366MB

sda5  ext3  4186MB   604MB
sda6  swop  4186MB     0MB
sda7  ext3  8381MB  3316MB
sda8  ext3 28697MB  1216MB
sda9  ext3 28648MB  6842MB
sda10 ext3  4194MB   100MB


It boots XP and Mandriva.  My intention was to install Kubunto 8.10 to 
replace Mandriva.  I thought I knew what I was doing until I got the 
Prepare Diskspace section of the installer.

After choosing to be guided over partition 8 I was offered a slide bar 
that seemed to change partition 8 from the initial setting of

sda8, 13.4GB 50% AND kubuntu 8.10, 13.4GB, 50%

I could move the bar left to increase the kubuntu partition/section but 
only reduce sda8 to 4.1GB 15% and kubuntu to 85%.

I chose this 15/85 ratio not fully understanding what I was doing but at 
least believing I was not altering the windows installation.

As I progressed I got to a stage where it confirmed I was about to create
partition 11 of SCSi1 (0,0,0) (sda) as ext3 and
partition 12 of SCSi1 (0,0,0) (sda) as swop

Now I am confused.

Am I really creating more partitions and how do I simply use the 
existing partitions for kubuntu.  Perhaps this was not a problem but I 
cannot see how creating more partitions is what I want to do and why can 
I not use the whole of partition 8 for kubuntu?

I abandoned it and am posting this question to be cautious.

Any guidance and help appreciated.

Stephen