It will install to the partition that you tell it to install to.
To install 10.04 to the same partition that 8.04 is installed on, just choose to install 10.04 to your current 8.04 root partition. From your bootinfo script output, your 8.04 root partition is /dev/sda5.
Since your output from your bootinfo script shows you do not have a separate home partition, you will need to backup any data in your home directory before you install 10.04.
When you install 10.04, this would be a good time to create a separate home partition.

Tommcd, Thank-you very much for your assistance. Since I had to re-load 8.04 previously, there is nothing saved in my Ubuntu system so if I did a fresh install of 10.4 it would be no problem as long as the bootloader works properly. I am not sure what you mean by adding a separate home partition though.

The home directory on any linux distro is used to store your user specific settings and all of your data. If you have /home on a separate partition, then all of your data and settings are preserved when you reinstall linux. See this for info on how to create a separate home partition during a Ubuntu install: http://www.psychocats.net/ubuntu/installseparatehome