Deploying with Capistrano - scaling up

Hi, 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 server 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? thanks Vivek