Now, if it's so easy, why don't you provide the original poster with step-by-step instructions how to do it?
Open a notepad document. Type "command.com" and save it to the desktop as "-whatever you want-.bat"
Open the file on ur desktop. It should bring up command prompt. Type in " at HH:MM /interactive command.com" where HH:MM is the military time 1 to 2 mins before your computers current time. For example if the time is 2:15 in the afteroon, you would type in 14:17. Close the command prompt and wait.
When your computer turns to the time u put in a command prompt will open. Press cntrl Alt delete and find explorer.exe under processes. End process.
In the command prompt that auto opened, type in explorer.exe (after the other explorer finishes closing, your start menu and desktop shortcuts will disapear) this will restart explored but you will be logged in under system. Alot of welcome screens pop up because this is probably the first te anyone has ever acessed this account. From here you can do whatever u need to do.
And that is how u hack a secure computer =]