Windows XP: Install Windows onto a USB Hard Drive

I successfully used the instructions here to install a fully working installation of Windows XP SP3 onto a 60G USB drive.
Luckily I had a Windows and Linux laptop to hand, so I used ISO Master on Ubuntu to edit the .iso, rather than WinISO, and my favorite K3b to burn the image.

With my laptop set to boot from USB as the priority, I can plug the drive in to boot Windows, or leave it unplugged to boot into Linux.

I haven't gotten around the page file warning on startup yet, but I plan to create some space on an internal drive to host it.