Difference between Inspiron and XPS's?

This is a pretty stupid question, but I still don't understand why there is a major price gap between the two.

Say why would anyone get a M1210 when you could get a 15-17" Inspiron with even better specs (T7100, Geforce 8600 GT, 2 GB ram) for around the same or even lower price?

 

Simple. The M1210 is a 12" that weighs 4.2lbs; the 15" Inspiron weighs 6.6lbs, and the 17" Inspiron is somewhere above 8lbs. The thin and light, almost ultraportable M1210 (and M1330) make for pretty decent notebooks to carry around, whereas the 15" Inspiron is much larger and thus harder to lug around. The 17" is way too heavy to even think about carrying around. If you have no need to carry the notebook around, then you probably don't need to think about the smaller XPS. If you do, its just about the only viable solution in Dell's consumer lineup.

 

In general, 14"-15" laptops are the cheapest. You pay more for either larger or smaller ones. For the larger ones, you're paying for a bigger display, and for smaller ones, you're paying for lightness and compactness and all those parts crammed into a tiny space.