Vista Install using WDS - Not picking up unattend settings

I am having trouble getting the Vista Install (Enterprise Edition) to pickup
my unattend xml settings from Windows Deployment Services (WDS).
Here's what I've done so far:
- Setup WDS on W2K3 R2 SP2.
- Added boot image (boot.wim from Vista Enterprise DVD)
- Added install image (install.wim from Vista Enterprise DVD)
- Created an unattend XML file (using Windows System Image Manager - no
errors reported)
- Associated the unattend file with the install image (in WDS)

Here's what happens at the workstation:
- PXE boots and finds boot image. I select it.
- Boots to boot image and prompts me for locale, etc.
- Shows install image and allows me to select it.
- Prompts me for credentials, disk parititioning, etc.
- Commences Vista Build
- Prompts me for EULA, time, etc.
- Completes build OK

Only trouble is, I've setup responses to most of these questions in my
unattend XML file to handle these queries.
Why isn't it processing them automatically?

Any clues?