The wubi installer is a big FAIL. This is because the download is 18gb and it does not have a resume function.
Download utorrent http://www.utorrent.com/downloads/complete/os/win
then download the torrent http://www.ubuntu.com/download/desktop/alternative-downloads 694 mb
You need to choose the RIGHT torrent . if you system has amb64 you need to download that.
you can download hwinfo to find out what system you have http://www.hwinfo.com/download64.html
After your download the iso
install magic iso (if you do not want to burn it to a cd or have an netbook which does not have a cd/dvd)
right click and extract the iso into a folder .
Then double click and enter the folder and double click on wubi
enter your user name and password you want to use when you log into ubuntu and then click next