For a very low-tech version, you can schedule a batch file to run whenever
you want. The batch file should only copy the mdb if there is no .ldb file.
Presence of an .ldb file indicates an active user, and as John said, the
copy will frequently be corrupt and unusable. Here's a batch file I've
installed for clients to interactively make local backups of the mdb from
the server to their workstation. You would omit the 'pause' statements if
you're scheduling it to run unattended, and you would probably want to add
some kind of logging.
@echo off
REM Cannot make a valid copy while database is in use
if Exist \\ServerName\ShareName\DBName.ldb Goto DatabaseInUse
echo Copying database to local disk...
copy "\\ServerName\ShareName\DBName.mdb" "C:\BackupFolderPath\DBName.mdb"
pause
exit

atabaseInUse
echo ERROR: Cannot copy database file while application is being used.
pause
exit