To install ubuntu from the wubi installer....follow these steps:
Step 1:Insert the CD/DVD or the Live USB drive that you created from this post
http://maitnoobsatwork.blogspot.com/2011/07/unetbootincreate-your-own-live-usb.html
Step 2: The autorun will launch the Ubuntu menu if it doesn't go to the CD/DVD or the USB
drive and double-click wubi.exe.
Step 3: Install ubuntu outside windows using the demo and full installation option...refer to post
http://maitnoobsatwork.blogspot.com/2011/07/installing-ubuntu-1004-from-cddvd.html
Step 4: Select install inside windows.
Step 5: Select the Lnaguage,Installation drive,username,password etc.
Click Install.
Step 6: Wait while the installer installs the files
Step 7: Reboot after the wizard finishes and select Ubuntu from the OS choice menu.
Step 8: Wait for the installer to finish copying files...reboot after the installer is finished.
Step 9: Select Ubuntu linux from the grub menu.
Step 10:Enter your username and log in.
Step 11: If you wish to uninstall Ubuntu later boot into windows and select Ubuntu and
click Uninstall in add/remove programs.