Small OS to install, Need a small OS Options

[Chefskin]

Good day to you all and thanks in advance for you help. I recently aquired a Asus Eee PC from my son 'cause he got a new laptop. I loaded Easypeasy on it and it works great.
The problem that I'm having is that this thing has almost no memory. Whenever I boot it up it gives me a message that there is only "71.3 MB disk space remaining" As you might imagine this does complicate things in that I can't download updates to the installed software.
So what I need is this, a really small distro or OS that I can install so that I have SOME space left on the drive.
The specs are as follows

Brand: Asus Eee Pc 4G Surf (sometimes known as a 701)
Internal memory: 3.5 GB
RAM: Unknown (sorry I can't seem to find it)
OS: Easypeasy 1.6

In case it matters I'm setting the machine up so that my wife can surf the net and research things for her work. As such it will need to have Openoffice and/or some other word processor that is compatible with Windows Word and Excel as well as a PDF viewer. Although if there is a PDF editor that would be an added bonus.

Any help will be greatly appreciated