Download USBMultiBoot
Formatting
Extract the files in USB_MultiBoot2.zip
Double click the executable named USB_MultiBoot2.cmd

Press any key to continue. The next window will look like this.

Select your Usb flash drive from the drop down box. Make sure the 'Quick Format' checkbox and 'Enable LBA' checkbox is checked. Once the format is complete Do Not close the PeToUsb window and USB_MultiBoot2 window. If a new window pops up which displays the contents of the Usb drive, close that window.
Extract the files in Bootsect.zip. Open a new command prompt window. Browse to the directory where you have kept bootsect.exe
Now type "bootsect.exe /nt52 P:" (without the quotes) and press enter.
Note P: is the drive letter of my USB thumb drive. Your drive letter may be different so make the change accordingly. This command writes the correct boot sector to your usb stick which allows the computer to boot from the Usb drive.

Press 1 and Enter. A browse window will open, browse to the location of your XP setup file ( Can be your cd-rom drive or some folder on the hard disk)
Press 3 and enter the drive letter of your USB drive. (its not case sensitive) After you have finished, press 4 to start the process.

Click on Yes to continue. The script will then copy windows XP to the Usb drive. This may take a while depending on the write speed of your Usb stick.

Click on Yes to continue. When the script finishes click on 'Any' key to close the command window.
Booting
Insert your Usb stick and start your computer. Make sure your pc is configured with your USB flash drive as the first boot device in the BIOS. If you have properly selected the flash drive as your primary boot device you will get a startup menu.
