Determining members of local groups via C#

public ArrayList Groups(string userDn, bool recursive)
{
    ArrayList groupMemberships = new ArrayList();
    return AttributeValuesMultiString("memberOf", userDn,
        groupMemberships, recursive);
}

public ArrayList AttributeValuesMultiString(string attributeName,
     string objectDn, ArrayList valuesCollection, bool recursive)
{
    DirectoryEntry ent = new DirectoryEntry(objectDn);
    PropertyValueCollection ValueCollection = ent.Properties[attributeName];
    IEnumerator en = ValueCollection.GetEnumerator();

    while (en.MoveNext())
    {
        if (en.Current != null)
        {
            if (!valuesCollection.Contains(en.Current.ToString()))
            {
                valuesCollection.Add(en.Current.ToString());
                if (recursive)
                {
                    AttributeValuesMultiString(attributeName, "LDAP://" +
                    en.Current.ToString(), valuesCollection, true);
                }
            }
        }
    }
    ent.Close();
    ent.Dispose();
    return valuesCollection;
}

public static bool IsUserInGroup(string username, string groupname, ContextType type)
{
    PrincipalContext context = new PrincipalContext(type);

    UserPrincipal user = UserPrincipal.FindByIdentity(
        context,
        IdentityType.SamAccountName,
        username);
    GroupPrincipal group = GroupPrincipal.FindByIdentity(
        context, groupname);

    return user.IsMemberOf(group);
}

private int validateUserActiveDirectory()
{
    IntPtr token = IntPtr.Zero;
    int DBgroupLevel = 0;

    // make sure you're yourself -- recommended at msdn http://support.microsoft.com/kb/248187
    RevertToSelf();

    if (LogonUser(txtUserName.Value, propDomain, txtUserPass.Text, LOGON32_LOGON_NETWORK, LOGON32_PROVIDER_DEFAULT, token) != 0) {
        // ImpersonateLoggedOnUser not required for us -- we are not doing impersonated stuff, but leave it here for completeness.
        //ImpersonateLoggedOnUser(token);
        // do impersonated stuff
        // end impersonated stuff

        // ensure that we are the original user
        CloseHandle(token);
        RevertToSelf();

        System.Security.Principal.IdentityReferenceCollection groups = Context.Request.LogonUserIdentity.Groups;
        IdentityReference translatedGroup = default(IdentityReference);

        foreach (IdentityReference g in groups) {
            translatedGroup = g.Translate(typeof(NTAccount));
            if (translatedGroup.Value.ToLower().Contains("desired group")) {
                inDBGroup = true;
                return 1;
            }
        }
    }
    else {
        return 0;
    }
}