I just read this info: Your Chromebook will let you load a new OS through a USB drive
If we can boot into the O/S of our choice soon with a chromebook then Linux booting becomes a quick boot possibility. I do not believe it is possible to boot windows from a USB stick, like Linux.
You should be able to pick up a cheap netbook on ebay and run winXP for your specific needs. I would clone the the winXP hard drive as a malware protection backup. You could also put a good Debian based Linux on the netbook and run win7 in virtual box for your needs.
Instead of trying to put windows on a chromebook.