If you forgot you Admin password, here is a quick tutorial.
Note: This method DOESN'T bypass the bios pass (if any). There are other ways to bypass bios password.
Download CIA Commander from here (trial). Run it and install it on a floppy disk.
Restart your pc and go to BIOS menu. Select to boot with the floppy.Save and exit bios.
You come to a blue screen. You have to select your partition (select the one where windows is installed on)
You come to a menu , choose User Manager
You come to a DIR Listing where you have to choose your winnt directory (windows 2000 : WINNT ; WINDOWS XP : WINDOWS) select it and press space. You see a listing of the available users. If not there should be a message that the administrator account is locked. Unlock it.
If there is a listing of the users select the user and press F3 to change the pass. Enter a new pass and press enter. You should get a message that the password has been changed successfully.
Congrats! You just changed the old and lost pass to a new one. Theres no way to find out the old password with this tool. Also i didn't try it with a flash memory.