s been done, restart the machine, choose grub in the menu, then it will auto enter Ubuntu live cd desktop environment. Next step is quite important, open the terminal (Applications—accessories--terminal), type the code as below:
sudo umount -l /isodevice
 And then double click the installer icon on the desktop to enter installation interface, when choose a partition, choose the one to install Ubuntu partition, set the partition format as ext3, choose “/” as hang point, during installation process, if error /isodevice cannot be uninstalled, then open Terminal and input:
sudo unmount –l /isodevice
7) Modify grub and add Windows boot menu  
After installation and restarting the machine, you will find there’s no way to enter Windows 7, which needs us to carry out next few steps:
Ubuntu, open Terminal, type: sudo gedit /boot/grub/menu.lst
Add the next code:
      title Windows  Seven
root (hd0,0)
makeactive
chainloader +1