If the OS is already installed and everything is running okay, you can manually delete all the files without looking at them. You can download a program called Revo Uninstaller (revouninstaller.com) to do a good job of deleting the unnecessary programs, does a better job than the Microsoft uninstaller. Also download a program called Ccleaner (piriform.com/ccleaner) to clean the registry and wipe the free space on the hard drive. Both of these programs are free by the way. I also run a diagnostics program (if I can) to make sure everything is okay.
Edit: There are more Linux distros besides the Ubuntu flavors. I am personally getting used to a distro called Linux Mint. It comes with everything pre-installed so that it works right "out of the box" like Windows does and is supposedly easier on the novice than Ubuntu is. When it comes to a Live CD, I prefer Puppy Linux. Now I have to learn how to use the terminal to wipe external USB connected hard drives.
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