function cerca (motore)
{
	var search_key;
	var search_string ;
	search_key = document.getElementById("txt_search").value;

	switch(motore) 
	{ 
		case 'google':
			if (search_key != "") 
				{
					search_string = 'http://www.google.it/search?q=' + search_key;
				} else {
					search_string = 'http://www.google.it';
				}
			break;
		case 'search_me':
			if (search_key != "") 
				{
					search_string = 'http://www.searchme.com/Initial.html#/0/&pi=0/&q=' + search_key + '/&ci=all/';
				} else {
					search_string = 'http://www.searchme.com';
				}
			break;
		case 'kartoo':
			if (search_key != "") 
				{
					search_string = 'http://www.kartoo.com/?q=' + search_key;
				} else {
					search_string = 'http://www.kartoo.com';
				}
			break;
		case 'wikipedia':
			if (search_key != "") 
				{
					search_string = 'http://it.wikipedia.org/wiki/index.php?title=Speciale:Ricerca&search=' + search_key;
				} else {
					search_string = 'http://it.wikipedia.org';
				}
			break;
		case 'ubuntu':
			if (search_key != "") 
				{
					search_string = 'http://packages.ubuntu.com/search?suite=default&section=all&arch=any&searchon=names&keywords=' + search_key;
				} else {
					search_string = 'http://ubuntu.com';
				}
			break;
		case 'ebay':
			if (search_key != "") 
				{
					search_string = 'http://shop.ebay.it/?_from=R40&_trksid=m38&_nkw=' + search_key + '&_nd1=See-All-Categories';
				} else {
					search_string = 'http://www.ebay.it';
				}
			break;
		case 'trova_prezzi':
			if (search_key != "") 
				{
					search_string = 'http://www.trovaprezzi.it/categoria.aspx?libera=' + search_key + '&prezzoMin=&prezzoMax=&sbox=sb';
				} else {
					search_string = 'http://www.trovaprezzi.it';
				}
			break;
	}
	location.href= search_string;
}