has a free (and excellent) office suite of software. It even reads .docx and .xlsx files created by Microsoft Office 2007 & Office 2010.
has many programs which can be run directly from a flash drive, including LibreOffice programs.
is a very nice web browser, also free.
is an alternate to Adobe Reader and has a smaller footprint.
Remember, anyone can write a website about catapults - that doesn't mean they actually know anything about them. So use more than one source (4 are required) and if you can suppliment online references with book references, even better.