I have several copies of aC installed and each one uses a different prefix in the table names. Work uses AB_, and personal copy uses CD_.

I'm not sure if this is what you're looking for.

A non-business edition would just be a advanced web-based to-do list. There are other projects that fill that need. Otherwise, there is always the option of not utilizing the clients portion - I have one installation that i use for keeping track of my personal projects (no collaboration with clients) and works just fine.

There's Stikkits, which is hosted; Tracks, if you've got a host with Ruby to run it with; and a host of other personal-productivity apps widely available. Just spend some time looking at the GTD community and you'll be awash in recommendations.