Create a VirtualBox guest machine for Linux Mint 9, see below for my configuration:
Now power up VirtualBox guest machine and mount Linux Mint 9 ISO.
Next would be install VirtualBox guest additions to make it to run faster, dynamically resize guest window, shared folders, etc.
From VirtualBox GUI, select Devices | Install Guest Additions... This will virtually insert the ISO into the CD/DVD. To mount it the GUI way in Mint, do hit on Menu | Computer. Then double click on the CD/DVD. Then drop to GNOME Terminal (Menu | Terminal ) and follow the following instructions.
There you go!!! Enjoy...