This article describes steps for creating a bootable USB drive to install Windows Vista, 7, or 8 on Ubuntu. I only tested the procedure for Windows Vista. You first need the tool unetbootin and an ISO image of the desired version of Windows (e.g. by ripping the installation DVD):
sudo apt-get install unetbootin
Then follow these steps:
- Afterwards, first format the USB drive as FAT32 because unetbootin has problems with recognizing NTFS-formatted driveds in its current version.
- Run unetbootin. It should recognize the USB drive. Leave the program open.
- Format the USB drive as NTFS (with boot flat enabled) and mount it somewhere (e.g. at /mnt).
- Go back to unetbootin and start creating the bootable USB drive by clicking OK.
For formatting, you may use the graphical tools GParted, KDE Partition Manager (command: partitionmanager) or the command-line tool fdisk.
-  Source of this solution from askubuntu.com