function check_form(form) {
	
	// Define email regex
	var emailExp = /^[\w\-\.\+]+\@[a-zA-Z0-9\.\-]+\.[a-zA-z0-9]{2,4}$/;
	
	if (form.id == "form_newsletter") {
	
		// Full Name
		if (form.fullname.value == "") {
			alert("Please fill in your full name.");
			form.fullname.focus();
			return false;
		}
		
		// E-Mail
		if (form.email.value == "") {
			alert("Please fill in your e-mail address.");
			form.email.focus();
			return false;
		}
		
		// E-Mail (Basic Validation)
		if (!form.email.value.match(emailExp)) {
			alert("Your e-mail address doesn't appear to be valid. Please correct it");
			form.email.focus();
			return false;
		}
	
	// Contact Form
	} else if (form.id == "form_contact") {
		
		// First Name
		if (form.name_first.value == "") {
			alert("Please fill in your first name.");
			form.name_first.focus();
			return false;
		}
		
		// Last Name
		if (form.name_last.value == "") {
			alert("Please fill in your last name.");
			form.name_last.focus();
			return false;
		}
		
		// E-Mail
		if (form.email.value == "") {
			alert("Please fill in your e-mail address.");
			form.email.focus();
			return false;
		}
		
		// E-Mail (Basic Validation)
		if (!form.email.value.match(emailExp)) {
			alert("Your e-mail address doesn't appear to be valid. Please correct it.");
			form.email.focus();
			return false;
		}
	
	} else {
		alert("Unknown form \""+form+"\"");
	}
	
	return true;
}