Do I need to register myself with the data protection act?

---

Hi, I am just starting my first therapy business. Obviously I will be taking clients' details and processing it (i.e. keeping it in a password protected Excel document - is this secure enough??). I will also use their info to send them vouchers/promotions etc. and will allow people to sign up for my newsletter via my website at some point. Do I therefore need to register with the data protection act? Shelley

---