The problem here is also that Dell randomly switches parts around on these things without changing the model name. If even their own support people can't keep it all straight, how are customers supposed to be able to? Apple gets away with it because they refresh the whole line at certain intervals, so "late 2010 macbook air" really means something, and also they point out stuff you should care about (e.g. Retina displays, but not e.g. CPU upgrades).
But ehy, every Dell pc has a service tag which identifies every pc (with that tag they even know the name of the owner) so they are supposed to know every part of the pc
The problem with Dell is they change part numbers so fast that a particular part number replacement not be available, you then run not well trained techs trying to figure out which newer part number actually works and is equivalent on your model.
Last year I purchased three XPS 17 laptops within 3 months of each other for a client. Each time I had to choose slightly different options as they didn't offer the exact same configuration each time.
