If you have a spare USB 2.0/30 flash drive or hard drive and want to re-purpose it for Windows To Go, you can follow the instructions at http://pureinfotech.com/2011/09/28/how-to-create-a-windows-to-go-usb-drive-in-windows-8-step-by-step/.  The guide works as advertised as long as you’re installing from Windows 8.  However, if you’re installing Windows To Go from Windows 7, running the last step will not configure the boot record:

bcdboot.exe h:\windows /s h: /f ALL

The reason is that the version of bcdboot in Windows 7 does not support the same options (in particular the /f option) as the version in Windows 8.

Wait a second…don’t I have Windows 8 already loaded on the USB flash drive/hard drive?  Yes, and you can copy the right version of bcdboot.exe to your Windows 7 machine or execute it in place. The right version can be found at:

h:\Windows\System32\bcdboot.exe

where h is your USB flash drive/hard drive letter.