Don't understand where all the hate for Treyarch comes from...well...besides the fact that their CoD games aren't quite as good as IW's. I'll admit that I have only played a small bit of CoD3, but I did finish WaW, and I thought it was quite good. They also have a number of other good games under their belt.
As for Vietnam and zombies, sorry, but this masterpiece beat them to the punch...