I had a bad experience with this database about two months ago but I realize now it was the idiots I was working for at the time. I just tried to port the CDC.NET code from Microsoft SQL Server (hard to install and configure for beginners) to the Firebird Open Source database (runs as embedded, local or networked) and I had the ADO provider replacing my MSSQL commands in less than one hour. There are a lot of administration tools for it, most of them less than 1 meg in size executables, contrast with 250+ megs for Microsoft SQL Express.
It's a great database - the best, in fact, when you consider it alongside all the other options. It has an automated install for both the SQL Server and the web service provider, so it should be really simple for amateurs to install it on their network if they just follow the prompts. At least it should be a lot easier than the very expensive and time consuming MSSQL server in comparison. You can set up your users in configuration files and never have to touch anything again. There will be a tabbed configuration window where you can do this the first time you start Vault OS and anytime thereafter you want to change something.
Because the database supports it, you should be able to run all the features in standalone mode with no server started if that is what you want. I'll see how it goes but I think that Firebird makes this fairly easy to do with a few configuration switches.