Change Local user settings from within c#

Question

I need to write a program that will take a existing local windows user, change the "Start the following program at logon field" in their environment tab and change the password to a new password.

I am using local users instead of AD, will System.DirectoryServices work? Also any tutorials on using System.DirectoryServices would be very helpful.

EDIT -- Ok, so I can find the existing user and I know how to update it. However I do not know what to put in the ???. What AD property represents "Start the following program at logon field" in their environment tab on the user settings page?

        DirectorySearcher search = new DirectorySearcher();
        search.Filter = String.Format("(SAMAccountName={0})", prams.user);
        search.PropertiesToLoad.Add("cn");
        SearchResult result = search.FindOne();
        if (result == null)
        {
            Console.Error.WriteLine("No user of name {0} in the system", prams.user);
            return -2;
        }
        DirectoryEntry entry = result.GetDirectoryEntry();
        entry.InvokeSet("???", new object[] { newProgramLognField });

EDIT two--- I now know that the field I need is "Parameters" however I this term is very hard to search for in the MSDN because it is such a generic term. I think I have the correct one because when i run the code

DirectoryEntry entry = new DirectoryEntry("WinNT://testComputer/testUser");
Console.WriteLine("connected");
string value = (string)entry.Properties["Parameters"].Value;
Console.WriteLine(value);

I get the result

P☺CtxCfgPresent????☺CtxCfgFlags1
????☺CtxShadow????*☻☺CtxMinEncryptionLevel? @☺CtxWorkDirectory??????????????????
??????????????"C☺CtxInitialProgram??????????????????????????????????????????????
????????????????????????????????????????????????????????????????????????????????
????????

I am guessing that InitalProgram portion is close to what I want, most likely the ??? after is is the existing path that is there but has be mucked up.

Now the question is how do I write correctly to it?

Edit-3 I try changing the casting from a string to a PropertyValueCollection however that just gives me the error at run time

Unhandled Exception: System.InvalidCastException: Unable to cast object of type
'System.String' to type 'System.DirectoryServices.PropertyValueCollection'.
at UserUpdater.Program.Main(String[] args) in e:\Visual Studio 2008\Projects\
UserUpdater\UserUpdater\Program.cs:line 91

Answer 1

My copy of the TechNet Script Repository says that this WSH script can be used to change the password.

Set objComputer = GetObject _
("LDAP://CN=atl-dc-01,CN=Computers,DC=Reskit,DC=COM")
objComputer.SetPassword "whatever"