I regard the SQLEXPRESS database as a hidden adjunct to ASP.NET.

Nobody needs know it is there. ASP.NET uses it for the personalization db. If you need to access data in Firebird or ADS, then you will need to write a specialized dnn module anyway. The core functionality of DNN needn't use another db. Just don't tell your boss it uses it

Your only problem will be if the SQLEXPRESS database expands to beyond its free limit - 3 GB I think. Make sure you shrink it every now and then.

Sanjay - I was just kidding. The point is that as far as dnn is concerned, Express isn't a database in the sense of a corporate database . It is the tool used to contain the dnn information needed to run the site. Yes, it could also contain corporate data, but you could also get that data from a different database for specific modules.