Oooookay, so basically the idea I have is that I would like to boot Windows XP over an AoE connection. This is no issue, however the problem comes when I want to have a single, read-only image as the base image and want to be able to boot multiple computers off this image.

Licensing issues aside (let's assume that this complies with all licensing issues, or we can think of it as just a conceptual "how could we do this"), the basic issues are thus:

• Each boot of Windows will require a writable AoE device
• The original disk image must be read-only to avoid changes in 1 boot affecting all boots
• (As far as I know) The AoE device must be a disk image, or some block device rather than a mounted file system (if this is not so, aufs could be used)

So the long and the short of this, from what I can tell is that we need a read only device that we can write to :P

At the end of a session, the changes to the device will be discarded, so these can be thought of as simple temporary sessions. This means that there is little concern with having changes to the original read-only image effecting the modifications to the "duplicate" images.

I would like to avoid duplicating the image for each instance, however if no solution can be reached then this could be a possibility (every boot, we can copy the image, give the fresh image to the new boot and remove when done)

Optimally, changes to the filesystem will be written to a different filesystem (much like what aufs does, however as stated earlier, afaik aufs only deals with 2 mounted file systems, whereas we need the end result to be an image or block device)

Sorry if I havn't explained this particularly well, however I've been trying to think of solutions, caveats and generally how to define the problem as I was writing. If you think that this idea is ridiculous because software x handles the problem better, I'd be very pleased to hear about it, but the basic requirement of temporary, network bootable windows xp sessions still applies.

Thanks in advance, I know I will get some super interesting discussion, if nothing else

Use qemu-kvm instead.
You can create relative images on hosts, the master image beeing read-only on a NFS share.
Readings will be on network, and writes on local so it's pretty fast.

Never used qemu before (but I thought I had a basic understanding of what it's purpose was before this xD... Now I'm not so sure). Will check it out and get back to you with the results/steps/questions

*EDIT:
Will this impact machine performance at all?... The Windows machines may need to do some reasonably heavy calculations (not disk-intensive, however could be ram/cpu-intensive)

Qemu-kvm uses the virtualisation instructions of the processors, so it roxx.
I use this setup for a long time and i enjoy it.