First of all you need Windows Vista or Windows 7 to do this. Plug in your USB and run the following commands. Keep in mind that this will erase all data on your USB.
DISKPART LIST DISK SELECT DISK 1 (Assuming 'list disk' listed your USB as 'disk 1') CLEAN CREATE PARTITION PRIMARY SELECT PARTITION 1 ACTIVE FORMAT FS=NTFS ASSIGN EXIT
After finishing all the commands, all you have to do is copy your Windows Vista / Windows 7 files on the USB.
Now you can just plug it in your computer, boot from it and the installation process will start.
