jQuery .support() implementation

Can someone take a look at the following plugin. I its a basic AJAX navigation plugin and it fades content into a div when menu buttons are pressed. What would be the easiest way to exclude IE 6/7/8 from recognizing the fade effect? I just want IE to not see the fadeOut/fadeIn part of the plugin:

$(function() {

var newHash      = "",
    $mainContent = $("#main-content"),
    $pageWrap    = $("#page-wrap"),
    baseHeight   = 0,
    $el;



$("nav#footer").delegate("a", "click", function() {
    window.location.hash = $(this).attr("href");
    return false;
});

$(window).bind('hashchange', function(){

    newHash = window.location.hash.substring(1);

    if (newHash) {
        $mainContent
            .find("#guts")
            .fadeOut(200, function() {
                $mainContent.show().load(newHash + " #guts", function() {
                    $mainContent.fadeIn(开发者_开发百科200, function() {
                    });
                    $("nav#footer a").removeClass("current");
                    $("nav#footer a[href="+newHash+"]").addClass("current");
                });
            });
    };

});

$(window).trigger('hashchange');

Since IE does not support cssFloat you can use jQuery $.support and issue the following conditional to detect if browser is IE if($.support.cssFloat) {....