We have something that sort of works, but I want to make it better. MOSS 2007,
UI and SPD tools only.

Have a custom list w two pre-defined and populated columns, approx. 50 rows.
Users type A are supposed to edit data in columns (hopefully not the pre-defined
ones). Users type B are supposed to only attach/upload files to rows based on
the pre-defined meta-data.

Sort of works. No way I know of to separate actions of users type A from type B.
(can have only 1 active edit form per list)((I know how to customize the one)).
And no way to see a linear list of attachments/uploads together w the two cols
of pre-defined meta-data.

But my real Q is, if we switch to a DocLib for the attach/uploads, is there
anyway for users type B, to start from the custom list, then "click away" and
have an upload go into DocLib TOGETHER WITH the pre-defined meta-data?