Hi, and welcome to LQ!
Quite frankly, I'm running Kubuntu on a PIII 800MHz CPU w/384Mb RAM with no problems. OpenOffice is included, and you'll only need to install the restricted-extras, which will include Java, Flash, multimedia codecs, and more. If it does turn out to be sluggish, install xubuntu-desktop. It's a little like Gnome, but lighter and much faster. CentOS and Knoppix work just fine, as well. OpenOffice can be installed later, as with any distro with which it's not included.
Not too sure what you can do with the laptop... IIRC, even Puppy (the smallest distro that I'm aware of) requires a minimum of 80Mb RAM.
Hopefully, someone else will chime in with something that will work.