The best way to get redhat or any other distrobution of linux that is available via download is to hit this site
http://www.linuxiso.org. They carry the latest and greatest. You can either download it or buy it for the cost of shipping (around $2 - $3). I have found the fastest way to get it is to install FlashGet which is a multiple download manager and then download the iso. Flashget will download it from 5 seperate FTP sites and you get the iso faster. Be warned though Flashget is not to be used with Easynews or any other site that doesn't like you to log into them multiple times.