VBA Security

Hi All

We have developed an Excel workbook with hundreds of lines of VBA code written for a specific application, and we would like to protect it.

Could someone give me an idea of what security options we have over and above the below (if any)?

We have protected all sheets and the workbook itself with passwords. The VBA itself is protected with a passoword.

My understanding is that VBA can be hacked into quite easily.....is there any way of adding another layer of security/protection without having to move to another platform altogether?

Thanks in advance

Sunil