Did the recent purchase of MySQL by Sun and the subsequent buggy releases kill the MySQL brand?
I whole heartedly embraced MySQL when it first came out as I used to be a
MySQL is still going strong, and will continue to.
Note however that SQL Server Express is limited in other ways; specifically, number of CPUs and limitation of RAM usage (1 GB).
Personally I prefer SQL Server over MySQL. It is much easier to work with. And applications properly developed for it can scale to enterprise level if you are careful.