If you're using a flat panel monitor, it's best to stick to a digital interface like DVI, Displayport or HDMI. The latter is usually limited to a maximum resolution of 1920x1200, but that is probably enough for 90% of gamers. HDMI also allows audio to be passed through if your monitor or TV has speakers, assuming your graphics card supports the feature (most recent ones do).
The multiple interfaces can be use simultaneously using multiple displays if you wish, and while many games support the feature, you might find that the 7850 lacks enough performance to get decent frame rates, depending on the games you play & the resolution, of course. There is always the option to add another 7850 in Crossfire mode, should you need a bit more oomph
