Long answer:
if the tables are already in your access database or are already linked to the access database (in tables view with a black arrow in one corner) then there is already a JET connection in place. If you need to connect to, or link another datasource then you will need to connect to it with a connection string or JET connection

Short answer:
If you can see the table in the table view then no.

Exceptions:
If you have linked into a datasource that requires a password and didn't check the 'remember password' box when you linked it, then you will either need to use a connection string anyway or just delete the link and relink but remember the 'remember password' option. this option is a pit obscure but it is in there somewhere

I'm off for the day but I or anyone else who reads this will be happy to answer any more questions on Jet