If Libre Office is too much for your computer you should consider using AbiWord for text processing and Gnumeric as an MS Excel alternative. They are not so powerful but extremely fast!
Abiword and Gnumeric are free. So are Libre Office and Open Office. That's the beauty of using Linux.I'm assuming that AbiWord and Gnumeric are both either free or very inexpensive. We have something quite similar for Microsoft Products, and if one can't afford buying Microsoft Office, they are free to download Open Office. I use it for one of my computers here at home.
I would like everyone to know that currently Abiword has an image embedding bug, at least for png images. When you save a file with images embedded, and someone else opens it with Abiword (or even if you open it up again after closing it!) The images become warped.I prefer using AbiWord as it is very simple and lightweight on the computer. I generally use it on my laptop, which is pretty old so it is nice because it helps it be a little faster. Other than that, I really like the fact that it is free. Microsoft's products are too expensive in my opinion.