I have the Cooler Master Storm Enforcer case, and it's a wonderful case. Should I keep the door open? I have the Cooler Master Hyper n520 Cooler cooling an AMD Phenom II x4 925 Quad-Core @ 2.8GHz, and would the intake fan for the cooler be hindered by having the door closed?
If you are referring to the side panel door then I will recommend against running with it open. The case was designed with the intent of having the side panel closed and airflow within the case benefits from it (or should by design). If you are referring to the front panel door, that's simply personal preference I think.
My $0.02 worth