A lot of this depends on your specific application: if the set of tasks is a fixed "wizard" workflow, then you can probably get by with conversations alone (using manual flush mode if it involves editing "live" entities). If your tasks themselves are varying or defined by complex business logic or performed by multiple users, then jBPM sounds like just the thing.
I'm just dipping my toes into jbpm myself, but there's quite a lot of docs here: http://docs.jboss.org/jbpm/v3/userguide/
The dvdstore example unfortunately has some really trivial business processes ... it'd be nice to think of some other longer-running processes. Maybe some simple supply chain processes like reordering/restocking? I'd take a shot at it myself, but as I mentioned, I'm a newbie to most of this stuff myself.