Now I'm playing with it. If you want better download experience use IE7 or IE8 (sorry IE6 no good). If you insist on FF like me you'll be downloading Java download manager like below first.
then you'll see this
depending on, I believe, your connection/reception speed the number of connections will vary. In the office I had 1~2 at home I had up to 4. The total download took less than 3 hours at home.
Installation took around 30 minutes depending on your hardware, don't forget to keep record of below as you may have to install it again later.