Use OpenACS 4, upgrading from OpenACS 3 is tedious since things don't map 1-to-1 between the versions. The core data model for OpenACS 4 has been stable for a while already. Officially, it's in Alpha 2, but a beta will come soon and Don's promising a first release soon after. No pressure Don 😉
Getting things from the CVS is easy, but you could get partially working code. Read the documentation for OpenACS 4. It's a good start. Then look at the code in some of the packages. I would start with the notes package because it's small and easy to understand.
