var win = null; 
function NewWindow(url,title,w,h,scroll){ 
LeftPos = (screen.width) ? parseInt((screen.width-w)/2) : 0; 
TopPos = (screen.height) ? parseInt((screen.height-h)/2) : 0; 
settings = 
'height='+h+',width='+w+',top='+TopPos+',left='+LeftPos+',scrollbars='+scroll+',resizable' 
win = window.open(url,title,settings) 
if(win.window.focus){win.window.focus();} 
}        
function checkform ( form )
 {
   // see http://www.thesitewizard.com/archive/validation.shtml
   // for an explanation of this script and how to use it on your
   // own website

   // ** START **
 if (form.name.value == "" ) {
     alert( "Please check you've provided your name." );
     form.name.focus();
     return false ;
   }   
    if (form.email.value == "" && form.phone.value == "") {
     alert( "Please check you've provided either your email address or phone number, so that we can contact you." ); 
      form.phone.focus();
 
     return false ;
   }     
   // ** END **
   return true ;
 }