Hey, thanks for the speedy reply.
To start with the app. will only have several users both in the field and in the office with one db.
However in the future there will be a group log in area and there will be seperate groups of users, each group having a seperate db.
The number of groups is open, and the number of users in each group is open. However I don't anticipate that the number of users in any one group will go above say 20.
The app. will have a lot of fairly complex financial calculations and queries too, if that is something that needs to be taken into account.