What you find there and other chains is a sign of their bargaining with the makers for EXCLUSIVES. It's not a real sign of this or that but they are a commercial venture with the goal of getting the public to part with money for the boxes they have on the shelves.
If they can get an exclusive then this will make it hard for the public to shop around and compare directly.
For example if you were BB and got the exclusive on the model W2XR machine then you could advertise without fear "we have the lowest price on the W2XR."
So there you go. Keep shopping and comparing.
PS. If your budget can stand the i7, get that.
I initially I was going to purchase a Studio XPS. The 8000 felt a bit cheap and light when I looked at one in BB, and suspiciously has already been replaced by the 8100. I've also read enough QC problems and dissatisfaction with Dell's non-business support to look at their business models, such as the Vostro, Optiplex, and maybe Precision models. I tried asking advice on Dell's boards but got zero response.
What I'm looking for is a fairly fast computer for basic stuff, but also non-pro photo work, video encoding/editing, 2D graphics work, music/movies/HDTV, maybe some light gaming. When I bought my last computer 9 years ago, I bought a something fast that would be obsolete as late as possible, and so far it's hung in there. I also want something that's built to last as long as I can stand it.
I understand that the more stable, reliable pick would be the Optiplex 780. But they don't offer the i7 processor. The fastest is the Quad Core series. Is the i7 that much faster/more advanced?
On paper, the Vostro looks like a better bet as far as hardware choices and future flexibility. But how is the reliability?