1.)Go to virtualbox.org and get the VirtualBox package for Fedora 8 or 9 and install it.
2.)Get the kernel-devel package: sudo yum install make automake autoconf gcc kernel-devel
3.)Run the setup file for VirtualBox: sudo /etc/init.d/vboxdrv setup
Making a backup of a VirtualBox Machine (.vdi) is more complex than just copy/pasting the image. The proper way to backup you VirtualBox Machine is:
VBoxManage clonevdi source destination
For example:
VBoxManage clonevdi ~/.VirtualBox/VDI/WinXP.vdi ~/WinXPBackup.vdi
It may take a while (depends on the size of the VirtualBox Machine partition.
Tip: Do not use the image whilst creating a backup. If you try to clone a .vdi while it’s in use, VBoxManage will fail.