The NetBootDisk can be booted via PXE!
I personally use NetBootDisk with PXElinux/Memdisk + a TFTP server + M$ DHCP on 2003 Servers. This can either be TFTPD32, or by using Windows Deployment Services's TFTP service.
PXElinux & MemDisk is a PXE bootloader for loading floppy images via PXE. Even though it has linux in it's name, you don't need any linux knowledge in order to get it to work. It's really just a couple of lines of config, then you can place the files on your friendly windows-based TFTP server!
This guide assumes you already have a PXE Server running.
1. To make a PXE bootable NetBootDisk, first make a workingNetBootDisk using a normal (or virtual) floppy disk.
2. Customise your Menu Options, and of course test it, so you can be sure that your (normal) NetBootDisk works. (Selecting the Universal PXE driver as a default is also recommended.)
3. Capture the floppy to a disk image, using WinImage or similar.
4. Place your disk's image file, on your PXE's TFTP Server.
PXElinux Menu Config
My personal choice is to use PXE linux as a network boot menu system. Then I have the choice of PXE booting in to Ghost Console, Memtest, NetBootDisk, Windows Deployment Services, and other bootdisks.
MENU LABEL ^N = NetBootDisk
kernel memdisk raw keeppxe
When Booting a NetBootDisk floppy disk image from PXE, you need to add the kernel raw option, otherwise the process will hang when XP DOS is "Starting..."
The keeppxe option will keep the PXE stack in RAM, so the Universal PXE NDIS2 driver can be used for ANY network card then - including (I suspect!) future cards!
(Thanks to everyone for helping with this!)