How to create default instance after creating a named instance?

Question

when installing SQLServer2005 developer edition (not express) I created a named instance:

MYSERVERNAME/MYINSTANCENAME

Is it possible to

Answer 1

Hm, when I use the "Change" button in Add/Remove Programs, SQL Server 2005 setup offers me the instance selection screen, and even allows me to list the existing instances. (I'm running XP SP2, by the way.)

I selected the "To install a new component, click here" link in the setup program, then selected SQL Server Database Services on the "Components to Install" screen to arrive at the instance selection screen that allows me to install a new default instance.