Using the BartPE plugin, it should be possible to start up a Windows recovery environment that you can run Bacula in. Note that these directions have not been widely tested at all, so be very, very careful in relying on them! There is no guarantee that they work at all, let alone in your environment! At a minimum, you should test them out on a test system before you even think about relying on them.
The wx-console that comes with the bartpe plugin is reported to not work very well. A simple solution is to simply run bconsole from another machine to trigger the restore.
Before using 'diskpart' to rebuild the partition table, you may have to first run 'net start daserver'.
Make sure to manually create any directories that bacula-fd needs, such as c:\bacula\working
You will probably need to boot into an XP recovery boot disk to run fixmbr and/or fixboot to recreate the boot loader.