First of all, make sure you have already installed both VirtualBox and Windows Vista guest. If you have not, here is the complete installation guide. Secondly, make sure you have updated your VirtualBox to the latest version (2.0.4). There are some issues in the earlier version which will cause the mounting to fail. In your Ubuntu machine, open up Virtualbox (Applications -> System Tools -> virtualBox). Highlight the Vista VM entry (make sure that it is in Powered off state) and click on the Settings icon at the top.
On the left, click on the Network. On the right, make sure that the Enable Network Adaptor and Cable Connected are checked.
On the left, click on the Shared Folders. Then, click on the icon on the far right. Select the folder that you want to use as a share point. Give it a name.
Click OK to close the Settings window. Boot up your Vista VM. Install the guest addition. (Skip this step if you have already done so)
Restart the Vista VM. Open your Windows Explorer, click on the Map Network Drive
In the Folder input text, enter \vboxsvr\sharename where sharename is the name of the share folder that you add just now. Make sure that the Reconnect at logon is checked. Click Finish
You should now see the shared folder mounted as a network drive.
That’s it.
