Hi
If you want to recover your data before you do this, then follow these steps to create a Ubuntu bootable disk and save your data to DVDS, a separate drive in your computer or an external hard drive.
Download the Ubuntu .ISO file.
Write it to a DVD using Imgburn that's it.
http://www.ubuntu.com/download/desktop
Select the 64 or 32 bit version.
Skip the form and select "Not now take me to the download" at the bottom.
http://imgburn.com/index.php?act=download
Install Imgburn and select, Write Image File to Disk.
In a few minutes you will have a disk that will boot your computer when Windows fails to start
Mike