I would like to consider ACT!2008 as a devevelopment platform and since I am a newcomer, I would like to ask : is it possible to use the fields of a custom table in groups and lookups in ACT!2008 ? ie if I store the cars of each contact, can then I use the cars properties (model, make) to select contacts in a group ?
The addition of custom one-to-many tables are rumored for the near future. You'd be better off waiting for that. If you can't wait you might want to build a stand alone MS Access database to store the one-to-many relationship.
You should sign-up on this ACT! sponsored developer site - http://actdevnet.com/. They have sample code there that you can use.