nt password changing

There is a book called Win32 Perl Scripting The Administrators Handbook (New Riders)

It has sample scripts that do things just that.

I believe these are freely downloadable on the website. All you need then is perl. www.activestate.com is oneof the favourites, but I would recommend not getting the latest version as I have found that it doesn't have all the modules (LANMan, NetAdmin, etc) that it needs to change things!

Cheers

To add to NewYork's answer:
On the NT4 Server cd, in the CLIENTS\SRVTOOLS\WINNT\I386 folder are all of the standard NT4 administrative tools, including User Manager. Just copy usermgr.cnt, usermgr.exe and usermgr.hlp into a local directory on the helpdesk computer, and build a shortcut to usermgr.exe.
Then, your helpdesk users can just double-click their shortcut, and (providing the helpdesk computer is a member of your domain, and that the helpdesk user accounts have enough domain authority) voila! The domain user account list is theirs. They could then select the appropriate user and change their password.
Easy!

Hi,using server manager is good option and you can also write your own script using Kix scripting tool.hope this will help you.
http://kixtart.org/links.html