So, for those of you using the XO Laptop (the One Laptop Per Child Project), this might help you update cleanly.
I wanted to upgrade to build 711, the latest stable release, but I didn’t want all the kiddie / programming activities that come with the activity packs. I had some problems installing activities one at a time, and finally made Web 86 work after installing Firefox and Browse, both of which failed to start and seemed to prevent me from installing Web at first.