Changing line colors and move text for menu navigation This code basically changes the color of the lines and move text for menu navigation.  Is there a simpler way of writing it?

$('.nav1 a').click(function () {
    $('.nav1').addClass("current_nav1");
    $('.sf_menu li').removeClass('current_nav2 current_nav3 current_nav4 current_nav5 current_nav6');
    $('#content, #home').slideDown(2000);
    $('#design, #seo, #galery, #about, #contact').slideUp(2000);
});

$('.nav2 a').click(function () {
    $('.nav2').addClass("current_nav2");
    $('.sf_menu li').removeClass('current_nav1  current_nav3 current_nav4 current_nav5 current_nav6 ');
    $('#content, #design').slideDown(2000);
    $('#home, #seo, #galery, #about, #contact').slideUp(2000);
});

$('.nav3 a').click(function () {
    $('.nav3').addClass("current_nav3");
    $('.sf_menu li').removeClass('current_nav1 current_nav2  current_nav4 current_nav5 current_nav6');
    $('#content, #seo').slideDown(2000);
    $('#home, #design, #galery, #about, #contact').slideUp(2000);
});

$('.nav4 a').click(function () {
    $('.nav4').addClass("current_nav4");
    $('.sf_menu li').removeClass('current_nav1 current_nav2 current_nav3  current_nav5 current_nav6');
    $('#content, #galery').slideDown(2000);
    $('#home, #design, #seo, #about, #contact').slideUp(2000);
});

$('.nav5 a').click(function () {
    $('.nav5').addClass("current_nav5");
    $('.sf_menu li').removeClass('current_nav1 current_nav2 current_nav3 current_nav4  current_nav6');
    $('#content, #about').slideDown(2000);
    $('#home, #design, #seo, #galery, #contact').slideUp(2000);
});

$('.nav6 a').click(function () {
    $('.nav6').addClass("current_nav6");
    $('.sf_menu li').removeClass('current_nav1 current_nav2 current_nav3 current_nav4 current_nav5 ');
    $('#content, #contact').slideDown(2000);
    $('#home, #design, #seo, #galery, #about').slideUp(2000);
});
Why do you need different navXXX and current_navXXX classes? Just have a single

var menus = {//you need some kind of mapping between elements clicked and menu items
  id1: '#home',
  id2: '#design',
  id3: '#seo',
  id4: '#galery',
  id5: '#about',
  id6: '#contact'
};

$('.nav a').click(function () {
    $('.sf_menu li').removeClass('current_nav');
    $(this).addClass("current_nav");

    var selected = menus[$(this).attr('id')];
    $('#content, ' + selected).slideDown(2000);

    for (var menu in menus) {
        if (menus[menu] != selected)
           $(menus[menu]).slideUp(2000);
    }
});