why not use dual booting, this means you can select either windows or ubuntu on startup so you can allways go back to windows if the installation goes sour or you muck up something while using ubuntu, the installer is fairly easy to understand so there's next to no chance of messing the install up.
Oh yea, ALWAYS BACKUP...
Info Page About Installing onto a Win8 PC: https://help.ubuntu.com/community/UEFI
And don't be nervous, Linux is a lot easier than people make out, granted you have to get use to the odd way it does stuff, but it's really nothing to get stressed about.
Good luck =D