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

What's there to think about? You should always buy a new computer without an *OS*. Then, install everything yourself. It's a real saving. And whether it's Vista or not is up to each individual! I'm still using 64-bit XP, and everything is fine.

That's clear! The point is different! You can buy a computer with XP, or you can assemble it yourself and install exactly what you need. But laptops come with Vista. I myself once faced the same problem when buying a laptop. 90% of all laptops had Vista; I searched for one with XP... I found a few, but in terms of components, they didn't suit me at all. I had to buy the one that suited me, but with Vista. Well, I thought I'd take a look and see what it's like. I looked... I won't say anything, I think you all know already...
And now, Vista is being pushed everywhere, both in laptops and desktop computers. I was choosing a new desktop, and most of them already come with Vista pre-installed; very few have XP, but thankfully, there are also completely bare ones.
But the problem is that a simple buyer will buy a desktop with pre-installed software so as not to bother with the installation, especially if they don't know how. And they will also advertise Vista to them, and they will fall for it. And if they refuse and ask for a bare computer, they will say: "Sorry! We don't live in America; we don't know our rights." We will sigh and buy it, come home, and delete it, installing the operating system we need.
The same goes for laptops; we'll buy one with Vista.
We don't know our rights, we don't want to know them, and we don't know how to use them. That's the whole problem. I think the sellers aren't entirely aware that the buyer can demand a refund for the software they don't need (again, legal illiteracy). There are only a few such buyers out of thousands of others who will buy without thinking.