Clone multiple CentOS VirtualBoxes

Step0:
Enable Virtualization Technology in BIOS  

Step1:
Install CentOS5.7 (Final) with GNOME. This is host machine

Step2:
Install VirtualBox on host machine

Step3:
Create a virtual machine with the following settings:
    System --> Motherboard:
        Chipset: ICH9
        Extended Features: Enable IO APIC, Hardware clock in UTC time
    Storage:
        Controller: SCSI
    Network:
        Attached to: Bridged Adapter

Step4:
Install CentOS5.7 (Final) on virtual machine which is created at Step3

Step5:
Copy file *.vdi to another directory (* = file name)
Execute the following command to change uuid of *.vdi file.
VBoxManage internalcommands sethduuid /path/to/*.vdi

Step6:
Create another virtual machine with copied hard disk.

Step7:
Start new virtual machine

Step8:
Repeat Step5~7 if you want to clone more virtual machine.