Also, just note that Ubuntu.....Linux in general......in my opinion and experience......tends to run much faster than Windows OS's.
Even from a Live environment you will be surprised just how responsive the OS will be for you.
It's not just you, I feel it's fair to say that most any long term Linux user will agree with this, as well as many who have tried it for the first time.
Though I run Linux Mint 17.1 MATE rather than Ubuntu, it runs rings around Windows. I've installed the 64 bit version of Linux Mint Xfce & MATE (depending on if the user wants more software installed out of the box) on Windows 7 computers that were struggling to run, and the computers ran much faster than when new. Most of the time, the person will fall in love at first sight & want Mint left on the computer.
For safety & just in case the person changes their mind, or wishes to sell it later (Windows gives it a higher value), I image the drive & create a recovery media set, normally this hasn't been done.
The greatest feeling of all is knowing that I've freed another person from the chains of Microsoft, usually for good.