We're currently installing a new ZCM 10 SP1 server and wish to use an
external MS SQL 2005 server for our database server.

The database installation went fine (using setup.exe -c). A local
install on a sql server running both a SQL 2000 server (name:mssql)
and a SQL 2005 server (name:mssql\data2K) instance (we're
transitioning between the 2 server versions). We properly installed
the db to the 2005 instance, all of the tables were created with
access for the default zenadmin user.

MS SQL Server configuration manager can connect with the zenadmin

When trying to install the ZCM 10 SP1 application to the remote SQL
server, the install cannot connect to the newly created database. Sql
server: mssql.mydomain.com, port: 1433, named instance: data2k, auth:
sql server, sql user: zenadmin, password: password

So far we've tried;

server: mssql.mydomain.com named instance:data2k

server: mssql.mydomain.com\data2k named instance:

server: mssql named instance:data2k

server: mssql\data2k named instance:

Port 1433 is the default port, and it is open.

Are there known issues trying to connect to a sql server running more
than one sql instance (especially where 2 versions of SQL Server
(2000/2005) are installed on the same physical server)?