Install Windows 7 from Ubuntu on USB Drive
Get your USB flash drive of 4GB or more, and an ISO-image of the Windows 7-DVD.
First you'll wanna format the drive. This can be done with gParted. To format NTFS you'll also need ntfs-3g.
sudo apt-get install gparted ntfs-3g
Now open gParted and format the drive to NTFS.
Download Unetbootin version 494.
Open Unetbootin, select DiskImage and browse for your Windows 7 ISO-image.
Check "Show all drives" and select your USB drive. If you're not sure which drive it is, open gParted again and check.
Click OK
Plug the USB drive into any machine and boot from it. It will start the Windows 7-installer.
Source: this tutorial.
Use the tool WinUSB for ubuntu. Packages are available from the WinUSB website
You can easily make this using winusb
package:
sudo add-apt-repository ppa:colingille/freshlight
sudo apt-get update
sudo apt-get install winusb