var page = 1;
var imgsrc = Array();
var linkhref = Array();

imgsrc[1] = "images/lineup_whatscool_1.jpg";
imgsrc[2] = "images/lineup_vertualculture.jpg";
imgsrc[3] = "images/lineup_hitech.jpg";
imgsrc[4] = "images/lineup_meetthekids.jpg";
linkhref[1] = "cool/index.html";
linkhref[2] = "virtual/index.html";
linkhref[3] = "hitech/index.html";
linkhref[4] = "meet/index.html";

function book_next() {
    page++;
    if (page > 4) page = 1;
    obj = document.getElementById("bookimg");
    obj.src = imgsrc[page];
    obj = document.getElementById("booklink");
    obj.href = linkhref[page];
}

function book_prev() {
    page--;
    if (page < 1) page = 4;
    obj = document.getElementById("bookimg");
    obj.src = imgsrc[page];
    obj = document.getElementById("booklink");
    obj.href = linkhref[page];
}