Encrypt AccesS File?

How easy is it for someone to use a non ACCESS (but easily available)
programme to alter numerical values in an ACCESS database table and save the
result in a way which continues to allow the db to be opened by ACCESS - I
want to prevent this (have already prevented shift-key access). Not sure
what programmes could do this but thought this is what the ACCESS encryption
facility is meant to prevent.

I encrypted an ACCESS database and opened it with Wordpad/Excel but found
that the numerical values did not seem to be encrypted and EXCEL could still
read the tables!

Other than a design change, if I want to stop users being able to alter
table values in this way, are there better ways than encrypting the mde file;
what other (unwanted!) deployment implications might encryption create? The
db was to be deployed as an unencrypted ACCESS 2002/2003 file format mde file.