Note you can install Android-x86 to an external disk like USB drive. You can choose an existing partition to install Android-x86, or you can create or modify partitions by choosing 'Create/Modify partitions'.
After seconds of booting, you will see a partition selection dialog.Boot from the Android-x86 installation CD/USB, choose the 'Install Android-x86 to harddisk' item, as shown below:.
Usually you should just use the latest image.