It is made even easier by using UBCD4WINv360.exe to make the boot files.

This tutorial is in three parts:

PART 1 - creating a UBCD4WIN installation

PART 2 - making a bootable USB flash drive that boots directly from UBCD4WIN BartPE files (i.e. not using an iso file)

PART 3 - adding the UBCD4WIN ISO file to your favourite grub4dos bootable USB drive

The following instructions are based on using a Windows XP SP2 Microsoft install CD and v3.60 of the UBCD4Win.

1. Create a folder on your hard drive called C:\XPCD and copy the entire contents of your Windows XP CD to this folder.
2. Download and run the UBCD4WINV360.exe file. Accept the defaults so that a C:\UBCD4WIN folder is created.
   If UBCD4WIN runs - Cancel it. Then right-click on the UBCD4Win shortcut - Properties - Compatibility Mode - check the Compatibility mode for Windows XP (SP3) box. This should fix the PreLogon error (see below) when using Vista/Windows 7 systems.
   
3. Do not allow it to search for your XP files (say 'No') and then set the Builder Source path to C:\XPCD
4. Set the Media output to 'Create ISO image' by clicking the radio button as shown below:
   
   
   
   
   
   
5. Click the Plugins button and check add any extra plugins that you want. I would suggest you do not add any for your first build.
6. Click the Build button and wait for the build to finish.
7. You should now have an iso file in C:\UBCD4WIN\UBCD4WinBuilder.iso
   and also a C:\UBCD4WIN\BartPE folder, which should have the following contents (or similar)
   
   autorun.inf
   BCDW
   BOOTSECT.BIN
   dban-Grub4dos.ini
   I386
   images
   isolinux
   menu.lst
   PROGRAMS
   syslinux
   WIN51IP
   WIN51IP.SP2

1. Run RMPrepUSB.exe and set the options as shown in the picture below:
   
   
   
   Note: the BartPE -> USB checkbox must be ticked!
   
   
2. Now click on the 6 Prepare Drive button and follow the prompts. The RMPrepUSBXP script should automatically run after the file copy stage to convert the files to a USB bootable file structure.
3. If the Windows system you are preparing this on is running Vista or Win7 or XP 64-bit, you also need to do the following tweak/fix. If you do not, when you try to boot from the USB drive you will see the following message:
   
   
   
   You will get this PreLogon error if you have used a
   Windows Vista/7 system to prepare the USB drive.
   
    To fix this problem before you find it:
   Create a folder on your USB drive under \MININT called \Registration (i.e. \MININT\Registration)
   Copy the file C:\Windows\Registration\R000000000001.clb from your Windows Vista/7 hard disk to make the file \MININT\Registration\R000000000001.clb on your USB drive.
   Note: Jim Nealand reported that he only had R000000000005.clb and R000000000006.clb files, so he copied these and it fixed the problem, so maybe just copying all of these will work?.
   
   Tip: to avoid having to do this in future, create a MININT\Registration folder under the folder PEtoUSB which is located under the RMPrepUSB installation folder (press F3 in RMPrepUSB to find it) and copy the R000000000001.clb file from your hard disk into that folder - e.g. if you installed RMPrepUSB.exe to C:\RMPrepUSB then place the file at C:\RMPrepUSB\PEtoUSB\MININT\Registration\R000000000001.clb. This means that whenever you make a new USB drive using RMPrepUSB and tick the BartPE->USB checkbox, the R000000000001.clb file will automatically be copied over.
   
4. (Optional) - if you wish to use this USB drive to boot other operating systems or images in addition to UBCD4WIN by adding them to the USB drive at a later date, you can also install grub4dos by simply clicking on the 'Install grub4dos' button in RMPrepUSB - say 'Yes' to copy over the grldr file. Note that a menu.lst menu file is already present on the USB drive!
5. Click on the Eject button and go test your new bootable drive!
   

Another example

Troubleshooting BSOD 7B

Blue Screen of Death 0x0000007B error

If you get this error when booting from some PCs (e.g. Dell PC or Acer TravelMate laptop) using any XP based USB bootable drive, the problem is usually caused by the WinPE/BartPE OS not being able to access the files on the USB drive. This is usually because of one of two reasons:

1. The version of NTDETECT.COM you are using is resetting the USB controller and thus the USB drive is no longer present. This may well be the problem if UBCD boots when emulated under QEMU but not on some real systems.

FIX: 1a: Use a modified version of NTDETECT.COM which does not reset the USB controller - see here

- OR -

2. You do not have the correct Mass Storage Drivers present in your XP/BartPE image files and so it cannot detect the USB drive when it switches to protected mode.
FIXES:
2a: Try changing the BIOS Menu Hard Disk access mode from 'Enhanced - AHCI' to 'Legacy' or 'Compatible' (mainly a fix for non-USB drive booting though!)
2b: Add mass storage drivers to your XP installation (UBCD4Win v3.60 does this automatically when you use the default build)
2c: Load the XP/BartPE ISO file into a ramdrive and use firadisk.gz. This requires more RAM but avoids the mass storage driver problems - though you may not be able to access all hard drives or USB drives in your system once you have booted to BartPE. See Part 3 below for details.

PART 3 - Adding the UBCD4WIN ISO file to your favourite grub4dos multi-boot USB drive

Tip: You can compress the iso file using 7zip to a GZip file (.gz extension). This achieves an almost 50% reduction in size and so takes up less space on your USB drive (you could then use a 512MB USB flash drive). Just copy over the compressed file /UBCD4WinBuilder.iso.gz in place of /UBCD4WinBuilder.iso and change the menu.lst entries.

Note: Regardless of if you use an .iso file or a .gz file, because the whole contents of the iso file is loaded into and runs from memory (RAM); you will still need a system with 1GB of memory (or more) and the amount of free memory once UBCD4Win has booted will be reduced by the same size as the files (i.e. 600+MB of files), so on a 1GB RAM system you may only have 200MB of RAM once UBCD4Win has booted.