BP is always to specify the database name you want to connect to (don't rely on the logins default database ! A sql instance can host multiple databases !)

Check out BOL for the jdbc driver: http://msdn.microsoft.com/en-us/library/ms378988%28SQL.90%29.aspx

IMO you should provide as many info as you can in your connection !

This will help with problem solving, monitoring, ...

e.g.

// Get connection

DriverManager.registerDriver(new com.microsoft.jdbc.sqlserver.SQLServerDriver());

String url="jdbc:microsoft:sqlserver://yourip;DatabaseName="yourdb";

Connection conn=DriverManager.getConnection(url,"username","password");