Cloning the old computer to create a VM has now failed several times, so these are the remedies we've tried:

• Removed all software I can do without.
• Cleared out temp files and any other cruft.
• Cleared lots of space on the target drive (an internal drive, as the USB drive didn't work).
• Defragged both source and target drives.
• Ran chkdsk /R on both drives.
• Disconnected all USB devices, replacing them with PS2 devices.
• Logged in as administrator.
• Turned off all non-windows services except the vmware ones.

VMWare Converter has now failed so utterly that we're having to give up on it, and use BartPE/Ghost to create a ghost of the C drive, and try to use that in VirtualBox.

We didn't expect this to be simple, but we weren't expecting VMWare Converter to fail so spectacularly.