Ok... I am seriously stumped on this one.   
I am trying to convert a database saved in Access (.mdb) into a
Paradox database (.db).
I have attempted simply changing the extension...which didn't work. 
Then I attempted downloading a program from
http://www.sharetool.com/Information_Management/Database_Programs/Database_Tour_1703.html
which says that it will convert the two... but as soon as I try to
import my file from access... I get a message that pops up saying
"database login:...enter username and password"
The problem is that the database is not password protected, so I have
hit a roadblock.  I have tried every password I can think of and it
still isn't working.
So my question -- what is the best way to convert a Microsoft Access
file into a Paradox file?

If you choose File>Export one of the options in Access (I have the
Office XP or 2002 version) is to export to Paradox format. I don't
know if you can export an entire database or if you have to do table
by table. I don't know if you can export anything other than data
(such as forms).

If your version of Access doesn't support Paradox format you could
still export to a text file format like .csv, which you would then
import into Paradox. You would still have to do this table by table
though (meaning you would have to recreate any relations between
tables and anything other than data).