Complete class reference updated for WPF (not yet tested). For backwards compatibility, previous Win32 code maintained in code comments (and just replace ‘Window’ with ‘Form’).

    /// <summary>
    /// Network drive interface from original application slightly modified to handle WPF windows.
    /// </summary>
    public class NetworkDrive
    {

        #region API
        [DllImport("mpr.dll")]
        private static extern int WNetAddConnection2A(ref structNetResource pstNetRes, string psPassword, string psUsername, int piFlags);
        [DllImport("mpr.dll")]
        private static extern int WNetCancelConnection2A(string psName, int piFlags, int pfForce);
        [DllImport("mpr.dll")]
        private static extern int WNetConnectionDialog(int phWnd, int piType);
        [DllImport("mpr.dll")]
        private static extern int WNetDisconnectDialog(int phWnd, int piType);
        [DllImport("mpr.dll")]
        private static extern int WNetRestoreConnectionW(int phWnd, string psLocalDrive);

        [StructLayout(LayoutKind.Sequential)]
        private struct structNetResource
        {
            public int iScope;
            public int iType;
            public int iDisplayType;
            public int iUsage;
            public string sLocalName;
            public string sRemoteName;
            public string sComment;
            public string sProvider;
        }

        private const int RESOURCETYPE_DISK = 0x1;

        //Standard	
        private const int CONNECT_INTERACTIVE = 0x00000008;
        private const int CONNECT_PROMPT = 0x00000010;
        private const int CONNECT_UPDATE_PROFILE = 0x00000001;
        //IE4+
        private const int CONNECT_REDIRECT = 0x00000080;
        //NT5 only
        private const int CONNECT_COMMANDLINE = 0x00000800;
        private const int CONNECT_CMD_SAVECRED = 0x00001000;

        #endregion

        #region Propertys and options
        private bool lf_SaveCredentials = false;
        /// <summary>
        /// Option to save credentials are reconnection...
        /// </summary>
        public bool SaveCredentials
        {
            get { return (lf_SaveCredentials); }
            set { lf_SaveCredentials = value; }
        }
        private bool lf_Persistent = false;
        /// <summary>
        /// Option to reconnect drive after log off / reboot ...
        /// </summary>
        public bool Persistent
        {
            get { return (lf_Persistent); }
            set { lf_Persistent = value; }
        }
        private bool lf_Force = false;
        /// <summary>
        /// Option to force connection if drive is already mapped...
        /// or force disconnection if network path is not responding...
        /// </summary>
        public bool Force
        {
            get { return (lf_Force); }
            set { lf_Force = value; }
        }
        private bool ls_PromptForCredentials = false;
        /// <summary>
        /// Option to prompt for user credintals when mapping a drive
        /// </summary>
        public bool PromptForCredentials
        {
            get { return (ls_PromptForCredentials); }
            set { ls_PromptForCredentials = value; }
        }

        private string ls_Drive = "s:";
        /// <summary>
        /// Drive to be used in mapping / unmapping...
        /// </summary>
        public string LocalDrive
        {
            get { return (ls_Drive); }
            set
            {
                if (value.Length >= 1)
                {
                    ls_Drive = value.Substring(0, 1) + ":";
                }
                else
                {
                    ls_Drive = "";
                }
            }
        }
        private string ls_ShareName = "\\\\Computer\\C$";
        /// <summary>
        /// Share address to map drive to.
        /// </summary>
        public string ShareName
        {
            get { return (ls_ShareName); }
            set { ls_ShareName = value; }
        }
        #endregion

        #region Function mapping
        /// <summary>
        /// Map network drive
        /// </summary>
        public void MapDrive() { zMapDrive(null, null); }
        /// <summary>
        /// Map network drive (using supplied Password)
        /// </summary>
        public void MapDrive(string Password) { zMapDrive(null, Password); }
        /// <summary>
        /// Map network drive (using supplied Username and Password)
        /// </summary>
        public void MapDrive(string Username, string Password) { zMapDrive(Username, Password); }
        /// <summary>
        /// Unmap network drive
        /// </summary>
        public void UnMapDrive() { zUnMapDrive(this.lf_Force); }
        /// <summary>
        /// Check / restore persistent network drive
        /// </summary>
        public void RestoreDrives() { zRestoreDrive(); }
        /// <summary>
        /// Display windows dialog for mapping a network drive
        /// </summary>
        public void ShowConnectDialog(Window ParentForm) { zDisplayDialog(ParentForm, 1); }
        /// <summary>
        /// Display windows dialog for disconnecting a network drive
        /// </summary>
        public void ShowDisconnectDialog(Window ParentForm) { zDisplayDialog(ParentForm, 2); }


        #endregion

        #region Core functions

        // Map network drive
        private void zMapDrive(string psUsername, string psPassword)
        {
            //create struct data
            structNetResource stNetRes = new structNetResource();
            stNetRes.iScope = 2;
            stNetRes.iType = RESOURCETYPE_DISK;
            stNetRes.iDisplayType = 3;
            stNetRes.iUsage = 1;
            stNetRes.sRemoteName = ls_ShareName;
            stNetRes.sLocalName = ls_Drive;
            //prepare params
            int iFlags = 0;
            if (lf_SaveCredentials) { iFlags += CONNECT_CMD_SAVECRED; }
            if (lf_Persistent) { iFlags += CONNECT_UPDATE_PROFILE; }
            if (ls_PromptForCredentials) { iFlags += CONNECT_INTERACTIVE + CONNECT_PROMPT; }
            if (psUsername == "") { psUsername = null; }
            if (psPassword == "") { psPassword = null; }
            //if force, unmap ready for new connection
            if (lf_Force)
            {
                try { zUnMapDrive(true); }
                catch { }
            }
            //call and return
            int i = WNetAddConnection2A(ref stNetRes, psPassword, psUsername, iFlags);
            if (i > 0) { throw new System.ComponentModel.Win32Exception(i); }
        }


        // Unmap network drive	
        private void zUnMapDrive(bool pfForce)
        {
            //call unmap and return
            int iFlags = 0;
            if (lf_Persistent) { iFlags += CONNECT_UPDATE_PROFILE; }
            int i = WNetCancelConnection2A(ls_Drive, iFlags, Convert.ToInt32(pfForce));
            if (i != 0) i = WNetCancelConnection2A(ls_ShareName, iFlags, Convert.ToInt32(pfForce));  //disconnect if localname was null
            if (i > 0) { throw new System.ComponentModel.Win32Exception(i); }
        }


        // Check / Restore a network drive
        private void zRestoreDrive()
        {
            //call restore and return
            int i = WNetRestoreConnectionW(0, null);
            if (i > 0) { throw new System.ComponentModel.Win32Exception(i); }
        }

        // Display windows dialog
        private void zDisplayDialog(Window poParentForm, int piDialog)
        {
            int i = -1;
            int iHandle = 0;
            //get parent handle
            if (poParentForm != null)
            {

                IntPtr hwnd = (new WindowInteropHelper(poParentForm)).Handle;
                iHandle = hwnd.ToInt32(); //poParentForm.Handle.ToInt32();
            }
            //show dialog
            if (piDialog == 1)
            {
                i = WNetConnectionDialog(iHandle, RESOURCETYPE_DISK);
            }
            else if (piDialog == 2)
            {
                i = WNetDisconnectDialog(iHandle, RESOURCETYPE_DISK);
            }
            if (i > 0) { throw new System.ComponentModel.Win32Exception(i); }
            //set focus on parent form
            //poParentForm.BringToFront();
            poParentForm.Activate();
            poParentForm.Topmost = true;
        }
        #endregion

    }

References
StackOverflow (blog), http://stackoverflow.com/questions/3465182/how-to-map-a-drive-using-c
PINVOKE (code references and snippets), http://pinvoke.net/default.aspx/Structures/NETRESOURCE.html
MSDN (info on class types and structures), http://msdn.microsoft.com/en-us/library/windows/desktop/aa385341%28v=vs.85%29.aspx