My rig is a general use rig as it is my main and only PC. I build it to be able to handle games and everything else I plan on throwing at it at least decently, such as Photoshop, Video editing/encoding, office work, etc.
A specialized system will excel at each of those fields better than my PC, but my PC won't suffer dramatically at any one area either. If you're doing a lot more Video work than anything else, I'd suggest a quad core as they do that type of work much better than a dual core.