After 4000, its meaningless. Basically, when they say 4200, they basically mean that it is the next step up, the next best processor. I think AMD gave up naming their processors in line with their performance vs the pentiums. The 4200+ dual core will provide the same speed as a venice 3400, which is 2.2 GHz when running a single application that does not use multiple threads. However, when you are using a multiple threaded application, or running many single threaded applications at once, the 4200 will basically complete the tasks up to two times faster than the 3400. Also, if you are on a tight budget, skip the platinum rev 2s and get ocz value ram(has wv in its product number). These will give you 240FSB with 2225 at 3.3-3.4 volts, and then you can run a divider to bring clock speeds up. There is very little performance difference, and you can use the extra 60 bucks to save up for a dual core amd x2.