I was recently adding EPM 2007 (Project Server 2007) to an existing WSS/MOSS 2007 setup (farm).
The installation worked a treat...then it came to the business end of the installation......to see the Project bits in action.

One gotcha I want to share with you:

1. Project Server allows configuration through an additional element within the MOSS SSP (already created in my case).
Project Server (group) -> Project Web Access Sites

When I first clicked on this guy, I got an error "Project Application Service does not exist or is not started..."
- trouble I thought.
Quick scan of the services on the machine - couldnt find it!

Trick: From Central Admin -> Operations -> Services on Server
- there is an extra 'Server Role', Project Application.
- select it and start the service (this installs the service as well)
- now from the main server role screen, (in my case - Single Server or Web Server...) the Project Application Service is listed and now started :)

Gotta be happy with that!