One option is to split the database into two (use Tools:Add Ins: Database Splitter). The Back End, which contains only the tables, and the Front End, which contains everything else and is linked to the tables in the Back End. This allows updates to the database w/o taking it off line for extended amounts of time (make copy of front end, make changes in copy, replace old front end with new).
Have the people access the front end. If performance is an issue, put a copy of the front end on each local machine (this makes distributing updates more complicated) but the back end has to remain on the network (available to all)