function showFields(){
  var reason = document.getElementById('reason');

  if(reason.selectedIndex == 0){
  //no selection
    showEls('none','none','none','none','none','none');
  }else if(reason.selectedIndex == 1){
    //wire transfer
    showEls('block','block','block','block','block','block');
  }else if(reason.selectedIndex == 2){
    //embedded
    showEls('none','none','none','none','block','block'); 
  }else if(reason.selectedIndex == 3){
    //quantity
    showEls('none','block','block','block','block','block');    
  }else if(reason.selectedIndex == 4){
    //info
    showEls('none','none','none','none','block','block'); 
  }
}

function showEls(hostnameS, osS, supportS, vatS, addressS, commentsS){
  var hostname = document.getElementById('hostnameContainer');  
  var os = document.getElementById('osContainer');
  var support = document.getElementById('supportContainer');
  var vat = document.getElementById('vatContainer');
  var address = document.getElementById('addressContainer');
  var comments = document.getElementById('commentsContainer');

  hostname.style.display=hostnameS;
  os.style.display=osS;
  support.style.display=supportS;
  vat.style.display=vatS;
  address.style.display=addressS;  
  comments.style.display=commentsS;
}

function canSubmit(){
  //validate input here
  var retVal = true;
  var errors ='';
  var email = document.getElementById('email').value;
  var name = document.getElementById('OFName').value;
  var reason = document.getElementById('reason').selectedIndex;

  if(name == ''){
    retVal = false;
    errors += "-You must provide your name.\n";  
  }
  
  if(!email.match(".@[-a-zA-Z0-9]+\(\\.[-a-zA-Z0-9]+\)+$")){
    retVal = false;
    errors += "-The email address doesn't seem to be valid.\n";
  }

  if(reason==0){
    retVal = false;
    errors += "-You must select a reason for contacting us.\n";
  }

  if(errors){
    alert("Your form could not be submitted because of the following errors:\n"+errors);
  }
  
  return retVal;
}