>My understanding of MySQL is that it is free if the web host makes it available but if you are going to distribute it as part of an application then you would have to pay per installation. We have several thousand customers for our app and I definitely do not want to have to pay site licenses or setup up a tricky database on each site. What appeals to me about the hype for Vistadb is size,xcopy installation,possible use on the web, promised speed, and promised stability. I live for the day when I don't have and more primary key violations - mostly caused by the OS writing garbage into the VFP table.

Another popular one is the FireBirdSQL
http://firebird.sourceforge.net/index.php

...but if this Vistadb does what it says it might be the way to go. We're going to setup a test for it here in the next day or two - be interesting to see how well it works.