I've been running SQL2k Developer on a box with one server as default
instance. I now installed SQL2005 as default instance... realizing only
later that I was "upgrading" the existing default instance.

However when I look at EM for 2000, the database "appears" identical to its
previous incarnation, i.e., databases, tables and sproces appear without
change. Yet when I open the management console in 2005, I also can view
this instance. I've not created any new objects in the database.

So, I'm not curious what the 2005 "upgrade" did to the existing instance and
the databases within and whether I will be able to continue using these as I
did with EM2000, or if some action starts making irreversible changes. I'm
running merge replication on several of those databases and the pubs within
also appear untouched.

I noticed that such upgrading does not upgrade the dbms and databases - if
you open the instance from sql management studio you can see its version -
for sql 2000 is 8.0, for sql 2005 is 9.0. I had to uninstall sql 2000 and
afair reinstall 2005 to make it running as 2005.
but there is probably way to stop the 2000 rdbms and using surface area
configuration utility run the default instance of 2005. it seems that if
there is instance naming clash, sql 2005 preserves old database engine.
peter