I'm not familiar with the distribution that runs on OLPC. If you check for an update from those folks, does it contain a more recent Firefox?

You can download the latest version for Linux, but I am concerned that if it doesn't work, you won't be able to go back, i.e., all your settings will be upconverted from your current version (which looks to be Firefox 3??).

Before upgrading, please make a back up copy of your active settings (Firefox profile) folder. This article has information on how to locate that folder:

Back up and restore information in Firefox profiles

Current downloads are available in your choice of languages here:

http://www.mozilla.org/en-US/firefox/all.html

Here is the information I found about Firefox on OLPC: http://wiki.laptop.org/go/Firefox

Good luck with your update and let us know how it goes.