function validate_required(field,alerttxt)
{
with (field)
{
if (value==null||value=="")
  {alert(alerttxt);return false;}
else {return true}
}
}

function validate_form(thisform)
{
with (thisform)
{
if (chkTerms.checked == false)
  {alert('you have to check terms and conditions');return false;} 
if (validate_required(email,"Email must be filled out!")==false)
  {email.focus();return false;}
if (validate_required(companyname,"Company name must be filled out!")==false)
  {companyname.focus();return false;}
if (validate_required(telephone,"Telephone must be filled out!")==false)
  {telephone.focus();return false;}
}
}