ImgCount = 2;
ImgArrey = new Array("img/top_img1.png", "img/top_img2.png");
CurImage = ImgCount - 1;

function ImgChange(){
	if (CurImage == ImgCount - 1){
		CurImage=0;
	}else{
		CurImage++;
	}
	document.top_img.src = ImgArrey[CurImage];
	setTimeout( "ImgChange()", 10000 );
}