Windows oem confusion!

A few weeks a go I purchased this beauty (LINK) and it came with windows 7 pro OEM installed with a restore partition. but apparently it also has a digital windows 8 key in the uefi. I contacted lenovo to get a disk for windows 8 but it would be $45, and I don't want to spend that much on it. so how can I back up my system or make a windows disk for it so i can reload at a later date.

btw I tried to create a disk with the built in lenovo software and the previous owner already made one and it wouldn't let me make a new one. I want to put Ubuntu on here but still want to be able to put windows on here if I so wish.

? if you install ubuntu onto it you can duel boot so you don't lose windows 

Could also just take out the HDD and install a new one that can be used entirely for Ubuntu. If you arent going to be using Windows just keep the other HDD in s safe place.

Dual boot works perfectly fine as mentioned.

That's no a bad Idea but if that HDD were to ever break I would like to be able to re install it onto a new one or at least copy it. 

         

     Then again I have been looking for an excuse to buy an ssd...