The specs you indicate are perfectly adequate for what you want to do. You will not need a graphics card with the Core i3. When passing sound via HDMI, you will not require a sound card. The motherboard used will be dictated by your choice in OEM (Dell, HP, Acer, etc.). USB 3.0 is not a necessity. It is useful if you plan to use external storage for copying large amounts of data and want the transfers to take much less time than USB 2.0.
