when you install windows 7 OS, the system ask for you enter username and password, then you have not enter any infomation.and press "shift + F10" popup dos windows,finally you enter below dos commad
ROBOCOPY "C:\Users" "D:\Users" /E /COPYALL /XJ
RMDIR "C:\Users" /S /Q
MKLINK /J "C:\Users" "D:\Users"