Adult Member Site, work with our desinger to help build the best

I am currently looking for a security person to help my new designer (who is TBD for the next couple of weeks) make my new site as secure as possible. My current site has numerous problems, security being one of them and I would like to make sure that the new site has been designed as securely as possible. I need someone to recommend the best programs to keep hackers out but allow the site to flawlessly work for those who are members. Please apply with your quote for this job (the site will be very large and have 3 seperate photo gallery thumbnail pages, numerous video downloads, streaming video, etc. I am also nervous because I am initiating a new pay per view and videos on demand section in my online store. This needs to also be very secure. Thanks, -H