var win = null; 
                          function NewWindow(mypage,myname,w,h,scroll,resizable){ 
                          LeftPosition = (screen.width) ? (screen.width-w)/2 : 0; 
                          TopPosition = (screen.height) ? (screen.height-h)/2 : 0; 
                          settings = 
                          'height='+h+',width='+w+',top='+TopPosition+',left='+LeftPosition+',scrollbars='+scroll+',resize'

                          win = window.open(mypage,myname,settings) 
                          }