Question: Everytime when I want to install the ubuntu, it calls me to download the ubuntu-12.04-wubi-amd64.tar.xz! Because of my poor network, it makes me crazy! How can I install the ubuntu 12.04 without downloading ubuntu-12.04-wubi-amd64.tar.xz?

Answer: 
Your best answer is to get the live-DVD. Please use this to boot and use the 'Try Ubuntu' option to make sure it runs OK on your hardware before attempting to install. You then have the option of using wubi recommended only if you use Ubuntu only occasionally or installing on a partition. Either way, make sure you can recover all data and the Windows operating system if something goes wrong.
<http://nl.releases.ubuntu.com/12.04/ubuntu-12.04-wubi-amd64.tar.xz>

Hey dude Download it from here and save it. And you install ubuntu again then copy this file into you disks directory which is in C : ubuntu/disks. 

I hope it will help :)