function emailvalidation(entered, alertbox)
{
with (entered)
{
apos=value.indexOf("@"); 
dotpos=value.lastIndexOf(".");
lastpos=value.length-1;
if (apos<1 || dotpos-apos<2 || lastpos-dotpos>3 || lastpos-dotpos<2) 
{if (alertbox) {alert(alertbox);} return false;}
else {return true;}
}
}


function emptyvalidation(entered, alertbox)
{
with (entered)
{
if (value==null || value=="")
{if (alertbox!="") {alert(alertbox);} return false;}
else {return true;}
}
}


function formvalidation(thisform)
{
with (thisform)
{
if (emptyvalidation(FirstName,"Please enter your first name.")==false) {FirstName.focus(); return false;};
if (emptyvalidation(LastName,"Please enter your last name.")==false) {LastName.focus(); return false;};
if (emptyvalidation(CompanyName,"Please enter the name of your company.")==false) {CompanyName.focus(); return false;};
if (emailvalidation(Email,"Please enter a valid email address.")==false) {Email.focus(); return false;};
}
}