Today I worked on a small MDT LiteTouch deployment solution at one of our customers. I thought this was going to be another easy day in the office.
After a day looking through log files, debugging and trying to figure out what was going on, I finally found the solution.

Thanks Jacques for posting this great tip.

When running WAIK 1.1 on a x64 Windows 2008 systems, you cannot generate a catalog for a captures x86 Vista or Windows 2008.
It’s a shame, really. But there is a workaround:

1. Copy the original catalog of your Vista x86 (INSTALL_WINDOWS VISTA ENTERPRISE.CLG) from your distribution share’s original OS (Distribution\Operating Systems\OriginalVistaEntSP1×86\sources) to the folder in which your imported your captured image (\Distribution\Operating Systems\MasterVistaEntSP1×86)
2. Rename the .clg file to a name that match your customized image in the form WIMFileName_ImageName (MasterVistaEntSP1×86_BUILD-VISTASP1CDrive.CLG in my case.)
3. Launch System Image Manager (do not use the Edit Unattended.xml button of Task Sequence Properties in MDT!)
4. Open your Unattended.xml file corresponding to the deployment task sequence of your captured image (\Distribution\Control\DEPL-VISTASP1X86 in my case). Ignore errors and message about catalog.
5. In the Windows Image pane (the catalog pane), right click the Windows Vista Vista and click Close Windows Image.
6. In the empty Windows Image pane, right click, choose Select Windows Image, change the file type to .clg, browse to the Operating Systems subfolder of your captured image and select the catalog file you just renamed (MasterVistaEntSP1×86_BUILD-VISTASP1CDrive.CLG).
7. Save your answer file

Now you can open it from the Edit Unattended.xml button of Task Sequence Properties in MDT!