Hi Ron,
to change the coordinate system you need to do the following steps. Open ArcCatalog and search your .mdb file in the directory. Tha you double click on it and a list of features and tables will appear. Right click on mu_Geometry, and choose Properties. In the second tab of the properties dialog you can choose your coordinate system and enable the new choice with pressing apply. Saving of the .mdb won't be necessary.
Good luck
//Ludwig