I am running 8.04 on an Acer Aspire 5100 that is dual booting
Vista. I
want to completely dump Vista and just run Ubuntu 8.10 (to be
installed from CD) only. My concern is backing up and restoring my
GnuCash and other files. The laptop has an AMD Turion 64 x2 Processor,
1 GB RAM, 160GB HDD and ATI Graphics.
Can someone offer some guidance, please?

You can back up your entire home directory found at /home/username onto a usb
key, DVDs, or an external drive. However, you will want to make sure that your
hidden files are visible. These files and folders all begin with a dot. To make
them visible in Nautilus you can either use the menu under View or press Ctrl+H.
Once you see all of the hidden files and folders copy them by copy and paste or
drag and drop to your back up drive. If it is a DVD it will likely need multiple
ones and is a bit trickier.

Once you have backed it up then you can reformat or repartition and re-install.
Once everything is done you can copy all of the files and folders into your new
/home/username folder. To repartition you should work from the Live CD and make
sure that your drive that you are working on is not mounted. If you don't need
two partitions then you can destroy one, but you should consider putting your
root on one partition and home on the other. That way you will never have to
move your data again if you re-install. You just re-use the same home partition.

All of the files that you will need will be in your home folder. The root folder
has system settings, but not data or user settings.