1. The reason you don't use flat head screwdrivers is because it is easier to damage the PCB of a motherboard or video card. The more wedge-like design is more harmful to components. Data from Intel showed that screwdriver accidents were either the leading cause or the second leading cause (I forget which) of artificial motherboard failure. There is a reason all your chassis screws are philips screws.
2. If you are going to be upgrading everything else I would go post in the
Building forum.