Software Programmer Questions

We are looking for someone to develop a security software similiar to Norton Anti Virus. I am assisting in this project as to hire someone on board the company. What type of requirements should I be looking for in the areas of expertise. I do not want to get someone that is under or overqualified. We are also looking for someone to develop a product like Quick Books as well. We are looking for someone to take a percentage of sales as we have lines of direibution in place. This is a unique project based position as the person will have to have an entreprenurial spirit as well.