Does the pre-installed software on the purchased computer include Windows Vista, and is that something you actually need?

That's a strange position.
Let's say you need a Porsche Boxster. You go to the dealership and say, "Hey, I'd like that black one over there. But take off the wheels, I don't need them, I have my own. And while you're at it, remove the seats and the steering wheel." I wonder if you'd get a wild, unrestrained laugh in response, or just a look of incomprehension ;)

You yourself feel that you've made a completely inappropriate comparison, right? It's absolutely irrelevant here, isn't it? Software (and the OS in particular) and hardware – there's no analogy to be made between a car and its wheels. I can't even imagine what a valid analogy could be between a car and a computer.

Hmm... but I'll try. You go to a car dealership and say you need that Porsche Boxster. And the manager starts telling you that it's a very new model with incredible capabilities, and it's sold as a package with a DRIVER who will drive you around, because you won't be able to drive it yourself. And they don't tell you that the driver costs xxx $. But if you ask if you can have the car without the driver, they say, "No, sorry, it's not sold separately." So, you end up buying it with the driver, you come home, you kill the driver, and you get behind the wheel yourself :D. But you still paid for the driver. Now, the picture should be somewhat similar.

And as for the wheels and steering wheel – no one is going to ask to rip the keyboard out of the laptop or remove the Wi-Fi card :D.

Consider the OS as part of the product you're buying. If it doesn't suit you, welcome to the world of custom builds.

But it's impossible to see it that way. I would gladly do it, but where can I find a service that offers custom builds? Are there many places where you live where you can assemble a laptop?

Added after 12 minutes

And with Vista, etc., you just need to be confident and know your rights. When I bought a laptop, they not only sold it to me without the OS (although it originally had Vista installed), but they also downloaded the drivers for XP from the website and burned them to a CD in front of me (because now the laptop only comes with driver discs for Vista).

But did they reduce the price of the laptop by the cost of Vista? If not, then that's not a solution, because simply removing the OS without lowering the price of the hardware can be done in almost any store.