Such a relatively small number of concurrent users should not present any major problems. As for data access strategies, there are many possible approaches (as you seem to already know). Regardless of the data engine, when I am working in VB as a front end, I prefer to use ADO, and I avoid the VB Data Environment. In fact, here are a few quick tips:

-- don't be overly tempted by the MSDE technology. This is presented by Microsoft as an alternative to Access -- basically, it is a scaled down SQL Server, but I understand that there are some concurrency issues with any more than 5 users. It's a proto-typing engine as much as anything, and you'll want to be careful with it.
-- avoid DAO -- the legacy VB/Access technology. Go with ADO.
-- be wary of the Data Environment. It's great for quick prototyping, but you sacrifice some of the really neat features of ADO, and you end up forgoing direct control over the objects you use. (I should point out, thought, that aome very knowledgeable programmers I know disagree with me on this one -- they like the DE a lot.)
-- I am not a great fan of Access dynasets. I prefer to pass SQL Select Statements or open Access tables (if they are not too large).
-- Access has some great tools for building SQL Statements. Don't be afraid to use it to build statements which you can then cut and paste into your VB methods.


Enjoy!