Best DB For Commercial Application

Hi,

I'm putting together a commercial application - one I want to sell through te Internet.  I'm very worried about someone 'hacking' to my tables once they are deployed and doing whatever with teh data.  I'm currently using Paradox, but I have access to create a dBASE table through P7 (of course) and I have Access97.  Which of these databases are the most secure for commerical applications.

I know I could add a password, but there are tricks all around on how to break the enturnal DB security schemes.  i also 'heard' encrypting and decrypting DB tables tend to have an adverse effect on them in the long run.  Can someone refer me to a good DB encryption program - preferably Freeware?

Thanks