How to open DOS before Window run's during start up

Following are the steps to follow :

1) make backup of logon.scr (present in SYSTEM32 folder)

2) make copy of cmd.exe (present in SYSTEM32 folder) to some
temp folder.

3) raname that new copy of cmd.exe to logon.scr

4) replace this new logon.scr (actually renamed from cmd.exe) with logon.scr (present in SYSTEM32 folder)

5) now restart the computer and at user logon screen wait for 15 minutes
until command window appears.

That's all, now you can use commands like "net user Administrator *".
also you can even access sam registry entries .

-- Regards,
Dhananjay