//Form validation code
	function checkform(of)
	{
		// Test if DOM is available and there is an element called required
		if(!document.getElementById || !document.createTextNode){return;}
		if(!document.getElementById('required')){return;}

		// Define error messages and split the required fields
		var errorID='errormsg';
		var errorClass='error'
		var errorMsg='Please enter or change the fields marked with a ';
		var errorImg='images/alert.gif';
		var errorAlt='Error';
		var errorTitle='This field has an error!';
		var reqfields=document.getElementById('required').value.split(',');

		// Cleanup old mess
		// if there is an old errormessage field, delete it
		if(document.getElementById(errorID))
		{
			var em=document.getElementById(errorID);
			em.parentNode.removeChild(em);
		}
		// remove old images and classes from the required fields
		for(var i=0;i<reqfields.length;i++)
		{
			var f=document.getElementById(reqfields[i]);
			if(!f){continue;}
			if(f.previousSibling && /img/i.test(f.previousSibling.nodeName))
			{
				f.parentNode.removeChild(f.previousSibling);
			}
			f.className='';
		}
		// loop over required fields
		for(var i=0;i<reqfields.length;i++)
		{
			// check if required field is there
			var f=document.getElementById(reqfields[i]);
			if(!f){continue;}
			// test if the required field has an error, 
			// according to its type
			switch(f.type.toLowerCase())
			{
				case 'text':
					if(f.value=='' && f.id=='firstName'){cf_adderr(f)}
					if(f.value=='' && f.id=='lastName'){cf_adderr(f)}												
					// check firstName, lastName, phone and email
					if(f.id=='firstName' && !cf_isFirstName(f.value)){cf_adderr(f)}							
					if(f.id=='lastName' && !cf_isLastName(f.value)){cf_adderr(f)}							
					if(f.id=='phone' && !cf_isPhone(f.value)){cf_adderr(f)}							
					if(f.id=='email' && !cf_isEmailAddr(f.value)){cf_adderr(f)}							
					break;
				case 'textarea':
					if(f.value==''){cf_adderr(f)}							
					break;
				case 'checkbox':
					if(!f.checked){cf_adderr(f)}							
					break;
				case 'select-one':
					if(!f.selectedIndex && f.selectedIndex==0){cf_adderr(f)}							
					break;
			}
		}
		return !document.getElementById(errorID);

		/* Tool methods */
		function cf_adderr(o)
		{
			// create image, add to and colourise the error fields
			var errorIndicator=document.createElement('img');
			errorIndicator.alt=errorAlt;
			errorIndicator.src=errorImg;
			errorIndicator.title=errorTitle;
			o.className=errorClass;
			o.parentNode.insertBefore(errorIndicator,o);

			// Check if there is no error message
			if(!document.getElementById(errorID))
			{
				// create errormessage and insert before submit button
				var em=document.createElement('div');
				em.id=errorID;
				var newp=document.createElement('p');
				newp.appendChild(document.createTextNode(errorMsg))
				// clone and insert the error image
				newp.appendChild(errorIndicator.cloneNode(true));
				em.appendChild(newp);
				// find the submit button 
				for(var i=0;i<of.getElementsByTagName('input').length;i++)
				{
					if(/submit/i.test(of.getElementsByTagName('input')[i].type))
					{
						var sb=of.getElementsByTagName('input')[i];
						break;
					}
				}
				if(sb)
				{
					sb.parentNode.insertBefore(em,sb);
				}	
			} 
		}
		function cf_isFirstName(str) 
		{
			return str.match(/^[\w-]*$/);
		}

		function cf_isLastName(str) 
		{
			return str.match(/^[\w-]*$/);
		}

		function cf_isPhone(str) 
		{
			return str.match(/\(?\d{3}\)?([-\/\.])\d{3}\1\d{4}/);
		}

		function cf_isEmailAddr(str) 
		{
			return str.match(/^[\w-]+(\.[\w-]+)*@([\w-]+\.)+[a-zA-Z]{2,7}$/);
		}

	}