I've noticed Dell will frequently change their models (especially notebook models). It's all hype. If you look closely, they use the same basic chassis for each one but just change the colors. Most of them contain the same hardware to some extent.
My recommendation is to configure all of the models and choose the one that's best for the buck. In general, it's best to go mid-range within a given model type. That means if you end up maxing out an Inspiron 6000, bump up to the Inspiron 9300. If you can barely afford the Inspiron 9300 and give it a minimul config, go down to a mid-range Inspiron 6000 (or whatever the next model down is).