You can download the latest version of XOOPS, as well as read more about this package, at www.xoops.org [1]. PHPNuke is at www.phpnuke.org [2], and PostNuke is at www.postnuke.org [3]. The WeBLog module for XOOPS is availab le from www.wellwine.net [4].
PHP is available at www.php.net [5], and MySQL is at www.mysql.com [6]. Many modern Linux distributions and nearl y all hosting providers come with PHP and MySQL already, so you probably do not need to install them.
Links:
[1] http://www.xoops.org
[2] http://www.phpnuke.org
[3] http://www.postnuke.org
[4] http://www.wellwine.net
[5] http://www.php.net
[6] http://www.mysql.com