Once you are brave enough to install Ubuntu Linux or another distribution of Linux, then you should check out Openoffice. This is an office application suite. If you haven't heard of Openoffice before, think of Microsoft Office to get the idea. And, just like everything else on this blog, it is a completely free and legal software you can use. It does everything you expect from an office suite to do. Also, the Openoffice project is supported by an enthusiastic community and keeps growing and improving.
Here is the link.