Backing up the MS Office files is easy. Just buy a USB memory stick - they're cheap and easy to use - plug it into your laptop, and wait for it to be recognised.
It will be assigned a drive letter. Go into Windows Explorer and you'll see it. double click on the icon, and the drive will open.In the left hand column of Windows explorer find the My documents folder where all your Office files are. Left click on the folder you want and hold the mouse button down. Now drag the fold across to the new drive and drop it. Your files will be copied to your memory stick. If you like you can simply copy the entire 'My documents' folder.
Do that to any other folders to want to back up. Reverse the process if you get another computer.
The size of the memory stick will depend on the amount of data you want to store, but I would imagine you'll be more than covered if you get a 16Gb stick. That's actually quite a small capacity; if your budget permits get a bigger one - they're always useful to have around.