Dual-Boot Macs: What voodoo is this

When we manually deploy dual-boot Apple devices, this sequence of steps works well:

1. Install OS X image over the network
2. Use Boot Camp to prepare the disk for Windows
3. Use a Windows XP installation disc to install vanilla Windows
4. Stop the installation where the setup wizard begins
5. Format the Windows partition and install our WIM image with ImageX

Why are steps 3 and 4 necessary? Why can't we just install our WIM? In fact, it would seem easier just to use Disk Utility to create a second partition and install Windows there. In this case, there wind up being three partitions, including a 200MB partition at the front of the disk.

Update: Just reproduced this again. Here are the steps so far. If anyone wants to chime in on why this behaves this way, I'd love to hear your theories.

1. Installed OS X image
2. Ran Boot Camp Assistant
3. Selected "Quit and Install Later" rather than inserting a Windows disc
4. Rebooted into WinPE
5. Applied my WIM
6. Rebooted to BootPicker screen
7. Selected the Windows installation
8. Machine reboots (to disk0s3 per BootPicker) to a black screen with blinking cursor.

Booting with the Option key held does not list a Windows volume.

In Diskpart, the volumes are all listed and the appropriate files are on C:. I checked boot.ini and ensured that it was configured correctly and set the partition as active.