Below mentioned is a real time scenario with Questions and Answers:

We have Presentation Server 4.5 on 2 servers. Everything is on our Server1. Server2 is currently just used as another Citrx server in the same Farm for deploying Citrix applications. We need to take Server1 down for maintnance. I need to move everthing to Server2 including the database. Both servers have Microsoft SQL Server 2005 Express Edition installed. The Citrix database is on Server1 in its Microsoft SQL Server 2005 Express Edition database. How do I move everthing to Server2 so Citrix Applications will still run when I shutdown Server1? What changes the primary Citrix Presentation server from Server1 to Server2? Since  server1 is not used anymore uninstall citrix presentation server before taking it out. It will make server2 the primary when you do that.

What moves the Citrx web interface to Server2? You will have to setup web interface on server2, export you config from server1 and import it to server2

What moves Citrix Program Neighborhood Client Agent server from Server1 to Server2? same answer as above.

What moves the Citrix Farm Metrics server from Server1 to Server2? Answer as the very first - uninstall presentation server from server1 and it will automatically move to server2

Specifics for moving Microsoft SQL Server 2005 Express Edition datastore which is not Access or MSDE? SQL Express is a newer version of MSDE, you can find the process here