hi guys i have a problem about the credentials will you please help me. When i try to run the code below into a machine that is not logged-In into our domain(where sharepoint resides) it always gives me an error.

Error Detail:
System.Net.WebException was unhandled
Message="The request failed with HTTP status 401: Unauthorized."
Source="System.Web.Services"
StackTrace:
at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
at WindowsApplication1.List_Service.Lists.GetListCollection() in C:\Documents and Settings\daimous\My Documents\Visual Studio 2005\Projects\BCMD\WindowsApplication1\Web References\List_Service\Reference.cs:line 133
at WindowsApplication1.frmindex.button2_Click(Object sender, EventArgs e) in C:\Documents and Settings\daimous\My Documents\Visual Studio 2005\Projects\BCMD\WindowsApplication1\frmindex.cs:line 732
at System.Windows.Forms.Control.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnClick(EventArgs e)
at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ButtonBase.WndProc(Message& m)
at System.Windows.Forms.Button.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoCompo nentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
at System.Windows.Forms.Application.Run(Form mainForm)
at WindowsApplication1.Program.Main() in C:\Documents and Settings\daimous\My Documents\Visual Studio 2005\Projects\BCMD\WindowsApplication1\Program.cs:line 17
at System.AppDomain.nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
but when i try to run it into machine that is currently logged-In into our domain it does not have any problem. but i want my windows application to work on both either under the domain or not.
Code:
            //List_Service is one of my Web References which is referenced to
           //Sharepoint List Service
            List_Service.Lists myservice = new List_Service.Lists();
            
            // Authenticate the current user by passing their default 
            // credentials to the Web Service from the system credential 

            myservice.Credentials = System.Net.CredentialCache.DefaultCredentials;

            // Declare an XmlNode object and initialize it with the XML 
            // response from the GetListCollection method.
            
            System.Xml.XmlNode node = myservice.GetListCollection();

            // Loop through XML response and parse out the value of the
            // Title attribute for each list.
            foreach (System.Xml.XmlNode xmlnode in node)
            {
                txtUsername.Text  += xmlnode.Attributes["Title"].Value + "\n";
            }
any input will be greatly appreciated...thanks in advance!