With a Dell its hard to say. It'll go down some possibly but it depends if Dell passes that onto its customers or not. On one hand I'd say yes but if the model/s you are looking at has some added features/components above what it had before you may not see much of a price drop. The up side is that you may get better components than they offered before the price change.
For example lets say the cpu price was to drop $100. Dell may keep the price the same but put in a better video card, or a bigger hard drive, or more RAM, etc., on that model. Dell could choose to do something like that. I think model choice will play a factor in this but for their low end models I would think you'd see a drop in price. It also depends on what the new price is on a particular cpu.