This is how you can create a bootable windows 7 usb flash drive. First you will need a usb flash drive. I would recommend using a 4GB one. Now you need to start up disk part. This is done by starting up command line prompt (windows key + R and cmd) and typing in
C:\> diskpart
now we need to find out the number of our disk. We do this using;
DISKPART> list disk
now we select the disk
DISKPART> select disk 1
we use the “clean” key word to clear all partitions.
DISKPART> clean
now we create a partition
DISKPART> create partition primary
now select the partition
DISKPART> select partition 1
now we need to format the partition
DISKPART> format fs=ntfs quick
now we mark the partition as active
DISKPART> active
we now need to set a mount point
DISKPART> assign letter=e
now quit disk part
DISKPART> exit
now we have an active partition and need to copy the windows 7 files to the usb drive.We can do this using “xcopy”
C:\> xcopy d:\ e:\ /E
Once this has finished copying we will have a bootable copy of windows 7 on a usb drive