Wimb , thanks for your help. Here is what I need. I need to use USB to instal two different versions of Windows XP pro, and All In One Windows 7. I managed to solve problem with copyng GLRDL file by downloading the latest RMPrepUSB program Now, If I format the drive using NTFS file system, I get error while booting from usb "Cannot find GRLDR" (or something). If I format the flash driver using FAT, everything is OK. I need NTFS because it is faster and one of my ISO's is 4 GB large. Can I use BOOT_USB that you suggested to install multiple version of Windows? After all of this, I would like to add portable versions of Windows XP and Win7, BootCD and UBCD. Is all this possible on one USB flash disk? Thanks for your anwser in advance