Craig,
You can use the Connection's ServerVersion property to determine the version number of the MDB.
e.g.
Dim connString As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\nwind.mdb;"
Dim oledbConn As OleDbConnection = New OleDbConnection(connString)
oledbConn.Open()
Dim version As String = oledbConn.ServerVersion