function facebook_over()
{
document.getElementById("facebook_button").src ="facebook_footer_rollover.png";
}
function facebook_out()
{
document.getElementById("facebook_button").src ="facebook_footer.png";
}

function tumblr_over()
{
document.getElementById("tumblr_button").src ="tumblr_footer_rollover.png";
}
function tumblr_out()
{
document.getElementById("tumblr_button").src ="tumblr_footer.png";
}