No, MsAccess is probably not the right technology. The issues are 3-fold:
(1) There are significant possibilities of corruption when an mdb is hit by multiple users concurrently. Data corruption is a bad thing.
(2) Additionally, most low-end backup systems will not backup open files. If you are using MsAccess, it is probably because of funding, which tells me your disaster recovery ability is probably not there, either.
(3) It is slow. The memory handling and performance of MsAccess is brutal and dependent on the desktop accessing the data. Heavy use of index Seeks can mitigate this somewhat, but then you are into a lot of recordset manipulation instead of SQL.
I strongly recommend for and data mart with over three users or 500meg you consider going one more level up to SqlServer. It will address many of your concerns, run only about $1500, and be an order of magnitude more reliable and usable system.