Can someone help me with my motivation letter?

Hello!! I am about to apply for a MSc program in Cognitive Neuroscience and I have some trouble with my motivation letter. I thought it would be a good idea to send it to you, in order to review it for errors and mistakes. I also have a problem with my letter's length. They say they want it to be around 300 words (in fact, not to be longer than one page on Microsoft Office Word), but mine is 500 and no matter how hard I tried, I cannot make it shorter..
Thank you for your time! I look forward to your reply!!
This is the letter I have written:

Dear Sir/Madam

The purpose of my letter is because I would like to apply for the MSc Programme *****, that starts in September 2012. I am particularly interested in the **** Track.
My decision to apply for this MSc Programme, relies upon various reasons. First of all, studying about how the human brain functions and also about how consciousness, memory and learning can be explained at the level of simple communicating cells, has been triggering my interest since I was in high-school. Since then, I have been dreaming a career as a researcher in the field of Neuroscience. Therefore, this Master’s Programme seems like the first step for me in fulfilling this dream. Furthermore, in my opinion, the research in the field of Cognitive Neuroscience has a lot to offer in many aspects of human life, since it is a scientific field highly applicable in many others, like psychology, medicine , economics and philosophy, and I would be glad to specialize in this highly multidisciplinary scientific field. I also find really impressive the fact that despite the advances in technology, there are so much to still be discovered about the human brain. It would be very important for me to participate in this attempt to uncover the secrets of human cognitive processes. In addition, the fact that the **** Master’s Programme is research-oriented played a major role in my decision to apply for this. I believe that it is essential to evolve one’s knowledge through laboratory practice in order to gain a deeper thought on all the principles. Another reason for my choice originates from the well-known reputation of the high qualified education system of the Netherlands. Having a chance to study in the Netherlands will give me the opportunity to experience one of the best educational systems in the world and be taught by professors and researchers highly recognized in the scientific society.
The several laboratory and theoretical classes in the course of Neurobiology, during my BSc studies in Molecular Biology and Genetics, gave me essential laboratory experience as well as an insight into the structure of the neural network and into the way both the healthy and the pathogenic brain works. I have also read many books about memory, learning and human behavior, that helped me get a detailed view concerning the theoretical knowledge about the brain, and made me even more passionate with the field of Cognitive Neuroscience. I believe I have the qualifications to complete this MSc successfully. I strongly desire that after finishing the MSc Programme in the University of Amsterdam, by the knowledge and experience gained, I could work as a researcher in the field of Cognitive Neuroscience, contributing to the revealing of the mysteries concerning the human brain.

Thank you in advance for reading my application.

I look forward to your approval.

Yours sincerely