ASUS Socket 939

I have custom built many computer systems over the years, but I feel like a new comer when trying to decide what board and chip set to use on a socket 939 system. I have used ASUS extensively and will use ASUS on this system. With all of the various chipsets and motherboards available from ASUS for the socket 939 I have reached to a point of total frustration. The more I research the duller my mind becomes and am asking for some help or suggestions.The computer will be used for research, a lot of it on the web, for graphics work and for preparation of presentations. I am not a gamer, am not interested in gaming, and do not have any games on my PC.

I know that the chipset will basically determine which motherboard to use. I am considering the VIA K8T800 PRO chipset, as the ATI and NVIDA chipsets seem to be more for gamers. Again my mind is awash from researching the various chipsets available for the socket 939 from the different chipset manufacturers, ATI, NVIDA, and VIA. I would like some input on which chipset would be best for general computing? Also, I was thinking about an AGP video card, but after research I feel like AGP is becoming a dinosaur. On the other hand it seems like the only advantage of PCI Express is for gamers especially in a dual configuration. Is there any real advantage of PCI Express over AGP for general computing? Would it be advantageous to go PCI Express over AGP?