How to get approver name from Task list using available sharePoint web service

Hi , 

I need to get the approver name for workflow item from sharePoint library in my windows application i can achive this via SharePoint server object model but if i need to achive the same using sharepoint webservice in MOSS2007 then how i can do this?

Please suggest. below code works for me i need similar using webservice.

foreach (SPListItem item in lib.Items)
                {
                    // Get the workflows associated
                    SPWorkflowCollection wfColl = item.Workflows;

                    foreach (SPWorkflow myWF in item.Workflows)
                    {
                        string wfName = myWF.ParentAssociation.Name;

                        if (wfName.Contains("WFApproval"))
                        {
                            foreach (SPWorkflowTask myWFTask in myWF.Tasks)
                            {
                                //SPFieldCollection spFldColl=myWFTask.Fields;

                                string approverName = myWFTask["AssignedTo"].ToString();
                            }
                        }
                    }

}