There is a thread in the Administration forum that you should read where Charles Culp discusses graphics cards. The V4900 seems to be at a really sweet spot for power versus cost. The V3900 may be adequate for what you want to do. I'm not sure what the differences are between the two CPUs, but Charles would also be able to help with that question. See his latest thread in the administration forum on suggested computer specs, or possibly his older thread (May 2012). I have a vague memory that the i7 may be 3 or 4% faster than the i5 at the same clock speed, but I may be confused about which CPUs were being compared. In any case, the Administration forum is the right place to ask questions about hardware.