Before reading GTD, I was a classic messy desk guy. If I had enough clear space on my desk to fit an 8 1/2 by 11 paper, it was a good day. I knew that my desk was messy, but some part of me accepted that as a function of who I was and how I operated. I believed that clear desks were for anal-retentive types who had to have everything in its place.
Now I understand that a clear desk leads to peace of mind, which in turn becomes an outlet for creativity and productivity. In one of his Ted Talks, David Allen uses an example of cooking. If a chef wants to make a beautiful and inventive dinner for her guests, it is very challenging to do it in a messy kitchen. Likewise, if you wish to have a creative and productive office space, a clear desk is vital. The clear surface of your desk allows you to spread out the project you are working on to find new ideas and solutions that were not evident before. Filing away anything that is not relevant to the task at hand allows your mind to focus distraction free.
So go ahead and GTD your desk until it is clear. Then you can advance to the next level in the martial art of work.