If it's a controlled environment, you could do worse than to check out using [link|http://www.ecomstation.com|eComStation] on the clients, with WSeB running WiseManager on the server. You'll be able to do the thin client thing quite easily, it's stable, and it runs on old hardware so you could sub in a stable build of mozilla on the existing machines. If one of the users stuffs up a box, you can usually restore the configuration in under a minute and have it back up and running... Wisemanager is available from the [link|http://www.serenity-systems.com|publishers of eComStation]; in fact, eCS started out as the fat-client component of the network management suite.