Here's a quick function that may be useful if you have to compare a bunch of value in a row. You can pass your parameters to it directly, as an array or as a JS object. It depends on jQuery for array/object conversion as IE < 9 doesn't know Array.map().

function anymax()
{
    var argv = anymax.arguments, argc = argv.length, max = false;

    if (argc)
    {
        max = argv[0];

        if (typeof max === 'object')
        {
            argv = jQuery.map(max, function(v, k) { return v; });
            max = argv[0];
        }

        for (i in argv)
            max = Math.max(max, argv[i]);
    }

    return max;
}