Thank you for your reply.
There are 4 Subnet in the HQ office and Mirage Server is not located in HQ. Mirage Server locates at their system center.
At this time, they do not use WinXP to Win7 migration using Minage. They will upgrade to Win7 manually at the work space in the system center.
And I agree no download over BR WAN at setting up BR.
Thanks,
AK