Help with multiboot usb disk with XP\Win7

So basically at work we have two cd images. One is an xp iso and one is for windows 7. My goal is two have one usb boot stick that when i boot it i can choose which one of those to boot. Ive come close but am finally stumped.

Im using XBOOT to create the multiboot filesystem with the isos. The Win7 iso boots fine. But when i boot the XP iso i get a bsod 0x7b after the xp boot logo screen. Ive seen this is common due to it looking for the hd drivers or such. Ive tried changing sata from ahci to compatibility. Ive tried the following work arounds.

1.) Using the hex edited NTDETECT.COM, it made no difference. I wasnt sure where it put this, so ive tried right on the root of the usb stick, as well as replacing the one in the root of the ecore.iso, which is the name of the xp image.

2.) Using firadisk in the menu.lst for grub.  I always got some error about the executeable not being right or something.
title ecore with firadisk.

find --set-root --ignore-floppies --ignore-cd /images/ecore.iso
map --mem /firadisk.gz (fd0)
map --mem /images/ecore.iso (0xff)
map --hook
root (0xff)
chainloader (0xff)

3.)The closest ive gotten is using YUMI which is another multiboot creator app. I would select ISO RUN FROM MEM when i would add the iso before it builds the usb disk. This results in just a black screen after the XP LOGO screen.

Since it seems my problem is getting the ecore.iso to successfully boot using a multiboot usb file structure we'll just concentrate on that and forget about also booting the win7 iso.

Heres the structure of the ecore.iso




And heres the structure of the usb disk after XBOOT formats it...





Now there's plenty of options in xboot, you can add the iso as iso emulation, hard drive emulation. IVe tried both, im not sure what the difference is. You can also use Syslinux or grub as the bootloader, ive tried both.