function set_bg(){
	bg=new Array();
	bg[0] = "url(./images/bg_pursuit.gif)";
	bg[1] = "url(./images/bg_190.gif)";
	bg[2] = "url(./images/bg_109.gif)";
	bg[3] = "url(./images/bg_gladiator.gif)";
	bg[4] = "url(./images/bg_pursuit_2.gif)";
	bg[5] = "url(./images/bg_b25.gif)";
	bg[6] = "url(./images/bg_beauf.gif)";
	bg[7] = "url(./images/bg_stucka.gif)";
	document.body.style.backgroundImage = bg[Math.floor(Math.random()*bg.length)];
}