A point to note about the Nikon D40, D40X, and the D60 is that these bodies do not have an in-built Auto-Focus motor.
This means, that you must consider very carefully what lenses you intend to use on your new camera.
So if you want to have lenses that Auto-focus you must buy only the newer AF-S type lenses that have their own built-in focus motor.
Otherwise, I think that all of these are fine.
If you want something a bit better, with more features then, I would advise looking at the older D80 which has just been replaced by the new D90 - So you could well find the D80 at bargain prices. These two do include a built-in Auto-focus motor so that they can use a much wider range of lenses.
Have a quick look
here for some current pricing info..