var win = null;

function CentWin(mypage,myname,w,h,scroll) {
 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+',resizable'
 document.MainForm.target=myname;
 document.MainForm.action=mypage;
 win = window.open(mypage,myname,settings);
 SubmitForm('');
 document.MainForm.target='';
}