I think that you should try Lubuntu - it is a great distribution which is very easy to install and will give you a good representation of a modern GNU/Linux setup. The other distros mentioned are great choices as well, but I think Lubuntu is very well polished.
I would stay away from Puppy - although it runs quick on pretty much anything you put it on, I do not think it is for beginners - some things can get a little hairy once you start playing with it.
But since this is not your main PC it does not really matter, install all of them (individually) if you feel like it -- that way you can see the differences and learn something new.
As far as an office suite for your other computer, definitely look at LibreOffice I have been using it for years (before that OpenOffice) in the educational, business, and personal setting with no major compatibility issues. I have been able to accomplish every task that I have had with this fantastic piece of software.
I have actually been using OpenOffice for a few years now.. It took some getting used to but now I like it.
OpenOffice should work on most Linux Distros?
open standards it does not matter what you use it all works and looks the same.
edit: that's correct, Puppy is ment to be used live, and has a bit more complicated hard disk install.
Last edited by mastablasta; July 30th, 2012 at 08:53 AM.