Encrypting Passwords in Sysprep File

In previous versions of sysprep the sysprep.inf file was deleted once sysprep
completed it's tasks. This was good because it did not leave a trace of the
credentials that were implied and used in the file to add the machine to the
domain during the sysprep process. Vista Sysprep seems to leave this file
behind. Does anyone know how to:
1) Force sysprep to delete the information once all passess have completed?
2) Encrypt any password information supplied in the file
3) Know any other workarounds for this security issue?

Thanks