Here is a script that you (being a domain admin) can run from your workstation and hit every powered on machine to change the local admin password. You need to create a text file that has all the machine names in you domain for the script to pull from. Here is the script:
'This script will take computer names from a file and change the local administrator account password to one of
your choosing. It will write the successes and failures to separate files as it goes along. This could be useful
in a small business where you want to keep the passwords the same or in the same format for all NT workstations.
'~~Script~~.
set fsomain=createobject("scripting.filesystemobject"

set failedmachines=fsomain.createtextfile("c:\failed.txt"

set successmachines=fsomain.createtextfile("c:\success.txt"
Dim txtcomputername
Dim passwrd
On Error Resume Next
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'Go thru each computer and change the admin password '
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
'Open the text file
set machines=fsomain.opentextfile("c:\pcs.txt"
'Start looping through the machine names in the file
Do While not machines.AtEndOfLine
txtcomputername = machines.ReadLine
'Goto the local Admin account of the machine
set usr = GetObject("WinNT://" & txtcomputername & "/administrator,user"

'IF you have an error, write to the failed file and do not attempt to change the password
If Err Then
HandleErr()
Err.Clear
Else
passwrd = "password"
usr.SetPassword passwrd
usr.SetInfo
successmachines.WriteLine txtcomputername & " was successful"
End If
loop
'Close all open files
txtdata.close
failedmachines.close
successmachines.close
'Present yourself a message so you'll know its finsihed
msgbox "Done"
set fsomain=nothing
set txtdata=nothing
set usr=nothing
set dellasset=nothing
Sub HandleErr()
failedmachines.WriteLine txtcomputername & " " & "was probably powered off. " & Err.Number
End Sub
Hope this helps.