My intention is for the PC to last longer than the 4-5 years that my past ones have. I'll use it for AutoCAD 2010, Starcraft 2, movies, and internet while my wife will use it primarily for programming in Visual Studio. RAM prices seems to have gone up so in an effort to save some money, I selected only 3GB of ram. When prices come down a bit, I'll upgrade to at least 6GB.
The cooler master case is a good case. You will be fine on stock cooler unless you plan on overclocking and as for your ram with using AUTOCAD and Visual Studio you really should get the 6 Gigs of ram for that type of work. I do work on AUTOCAD and I use every bit of my 4GB I have.