function checkMail(mail) 
{
var check = RegExp('^[_a-z0-9_-]+(\.[_a-z0-9-]+)*@[a-z0-9_-]+(\.[a-z0-9-]+)+(\.[a-z0-9-]+)*$', 'i');
if (check.test(mail)) 
{
return false;
}
else 
{
return true;
}
}

function check()
{

if (document.getElementById('FirstName').value.length=="") 
{
alert("Please fill in * First name.\n");
return false;
};
if (document.getElementById('LastName').value.length=="") 
{
alert("Please fill in * Last name.\n");
return false;
};

if (document.getElementById('Email').value.length=="") 
{
alert("Please fill in * Email.\n");
return false;
};
if (checkMail(document.getElementById('Email').value)) 
{
alert("The email address you provided is invalid! Please correct it. \n");
return false;
};

if (document.getElementById('Zip').value.length=="") 
{
alert("Please fill in * Zip.\n");
return false;
};
if (document.getElementById('Phone').value.length=="") 
{
alert("Please fill in * Phone.\n");
return false;
};
if (document.getElementById('Media').value.length=="") 
{
alert("Please fill in * Media.\n");
return false;
};
if (document.getElementById('OS').value.length=="") 
{
alert("Please fill in * Operating system.\n");
return false;
};
if (document.getElementById('System').value.length=="") 
{
alert("Please fill in * System type.\n");
return false;
};
if (document.getElementById('Capacity').value.length=="") 
{
alert("Please fill in * Media Capacity.\n");
return false;
};
return true;
}