This article outlines a possible issue at step 6.4.1 where the conversion will fail if a source machine that has a dynamic non-system disk has a non-volume partition
This problem is due to the method in which Windows upgrades a basic disk (which already has existing partitions) to dynamic. Windows will recognize any unallocated space as a partition and sets its partition type to dynamic (0x42). This can be verified by running the DMDIAG utility from the Windows 2000 Resource Kit.
This problem will not occur if an unallocated basic disk (i.e. no existing partitions on the drive) is upgraded to dynamic disk, before creating the simple volumes. Doing this will bypass the partition table in the Master Boot Record during the upgrade process and Windows will not incorrectly set the partition type.