Deploying with Capistrano - scaling up

this may be a stupid question but , just want to ask anyway..
I have a working rails application and capistrano deploy setup (cap
deploy works great)
on one machine..I want to add more machines preferably one for web
and another for a db.
What steps do I need to take to make this work..before just adding the
domain names
in the capfile and running cap deploy..

I am especially doubtful about the database machine..should both the
app and the db machines have copies of the rails app? ( i need to run
some daemons which I think i will run from the db machine)

Are there any resources out there?