We want to port it over to a design whereby each entry is a separate thread, with the entry itself being the first post in the thread and the comments following it. Viewing somebody's journal is then purely a question of selecting all the first posts from all the threads created by that person... I don't know why it wasn't done this way in the first place but I've not yet seen anything that explains it.
I've also taken the opportunity to play around with ASP.NET a little bit, because I think it could be used for providing the RSS feeds. And, aside from having to bludgeon it a bit to be content outputting XML without HTML, it's been a very smooth experience - SqlDataSource sits neatly between the database server and my code, and XmlTextWriter makes generating the RSS itself very easy.