Make your USB drive bootable by using RMPrepUSB.
Saving files is up to 10% faster if you first format your SD card or Flash drive using RMPrepUSB (FAT32).
RMPrepUSB is a user-friendly Windows graphical front-end which calls it's brother application RMPartUSB (which does all the hard work!).
RMPartUSB is a Windows command line utility and does not have a GUI and can be used in batch/script files (type RMPartUSB to see help/usage text in a Windows command console).
RMPartUSB makes a partition of any size and is primarily intended for USB Flash Drive (UFD) memory sticks, although it can be used on USB hard drives or USB card readers to create a bootable partition or even non-USB drives.
RMPartUSB also places boot code on the USB device for either XP/WinPEv1 (ntldr), Vista/WinPEv2/Win7 (bootmgr), MS-DOS (io.sys) or FreeDos (kernel.sys).
RMPartUSB does not place any files on the UFD - you must copy these over yourself or set the Copy OS Files option in RMPrepUSB to copy over the contents of a folder of your choice.