Use Nitroshare to transfer files between the Virtual Box host and guest machine.

Step one: Download Nitroshare from the website.  https://launchpad.net/nitroshare

Step two: Install the same version of the Nitroshare.

Step three: If you use Nitroshare under the Virtual Box, check the network settings. The Virtual Box network of the host and guest must use the "bridged mode" and should also in the clacc c netmask. 

Step four: Run the Nitroshare in virtual box host and guest machine. Check the Nitroshare settings. Remeber to type the Machine name.(Important!!!)

Step five: Drag and drop files on the Nitroshare icon to transfer files.

Nitroshare Q&A:

Q. unable to find an ipv4 broadcast and netmask address.....

A: Right click on the nitroshare icon at the taskbar. Check the nitroshare settings and remember to type the Machine name. 

Q. Firewall settings

A. Open the firewall 41720/UDP 41721/TCP

[virtual box]

[host:windows7 guest: xp & ubuntu(ezgo)]

[Nitroshare settings]

[Nitroshare setting: Machine name]