Finally, I have discovered a very simple utility from Microsoft to create a bootable USB flash drive to install Windows. I used this to create a Windows 2008R2 installable flash drive, and it works great. However, this utility only seems to work for certain versions of Windows, and only Windows.

http://www.microsoftstore.com/store/msstore/html/pbPage.Help_Win7_usbdvd_dwnTool