Installing Windows XP through Pen Drive
I made an ISO out of my WinXP Pro install disk, but Pebuilder/PeToUSB and UNetBootin don't seem to be up to the task of making it boot from my USB pen drive.
Give the instructions from this answer on ServerFault a go.
EDIT: I have re-located a tool called WinSetupFromUSB_0-2-3.exe (found loose on Google).
I am currently using this tool to install WinXP on the remaining partition space on my MSI Wind. So far so good, it is currently installing XP from my USB.
Will update this answer if everything works out...
UPDATE: The install worked perfectly. After the USB is built you first need to boot up off the first option in GRUB. Once the initial windows partiotioning and install is done boot off the USB again but wait for a second option to appear. Then select what HDD and partition the install was placed on, then it will run through the second part of installing windows (GUI part). This is needed because otherwise you will get hal errors.
This seems like the easiest way to get an XP installer onto a USB.