Both FireFox and ThunderBird have received updates to v1.0 PR2 and v0.9 respectively. Both updates feature a few new features, but mostly, they squash a massive amount of bugs. Updating is recommended if you have any previous version installed. What? You don’t have FireFox or ThunderBird installed? If you have a Mac, then you can get along fine with Safari and Mail.app (Some exceptions do apply. In that case, use FireFox and ThunderBird), but if you have a PC, then these two apps are a must.