The default interval for password changes for a computer/trust
account can be modified as follows:
Start the registry editor (regedit.exe)
Move to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Netlogon\Parameters
From the Edit menu select New - DWORD value
Enter a name of MaximumPasswordAge
Double click the new value and set to the number of days
Close the registry editor
In NT 4.0 this value is only available for machines with Service Pack 4 and
for all versions of Windows 2000. Values can be in the range of 1 to 1,000,000.
If the above options do not provide enough security for you, download Access manager for Windows.
Access manager provides much more security than standard ways in Windows.
More articles about Security