This script does 3 things. And when you read it, just know what it does those 3 things 3 times, to try and support more browsers. All 3 sections should do exactly the same stuff.
It works on a list of links, and when you click one link it changes its color to black, makes it underlined, and shows a specific area.

This works fine in FF, and does change the visibility in FF, but not IE.
Code:
var previouslayer = 'monday';
var previouselem = 'mon';
var vis = 'visible';
var hid = 'hidden';
var non = 'none';
var und = 'underline';
var blue = '#506EA0';
var black = '#000000';
function show(layerToShow)
{
    var elem = layerToShow.substring(0, 3);
    if (document.all) //early IE
    {
        //i dont know what to put here, everything i add breaks it
        eval( "document.all." + previouslayer + ".style.visibility = hid");
        eval( "document.all." + layerToShow + ".style.visibility = vis");
    }
    if (document.layers) //other
    {
        document.layers[previouslayer].visibility = hid;
        document.layers[previouselem].textDecoration = non;
        document.layers[previouselem].color = blue;
        document.layers[layerToShow].visibility = vis;
        document.layers[elem].textDecoration = und;
        document.layers[elem].textDecoration = black;
    }
    if (document.getElementById && !document.all)
    {
        prev = document.getElementById(previouslayer);
        prev.style.visibility = hid;
        prev2 = document.getElementById(previouselem);
        prev2.style.textDecoration = non;
        prev2.style.color = blue;

        nex = document.getElementById(layerToShow);
        nex.style.visibility = vis;
        nex2 = document.getElementById(elem);
        nex2.style.textDecoration = und;
        nex2.style.color = black;

    }
    previouslayer = layerToShow;
    previouselem = elem;
}