Xsever wroteThe world is evolving. If we go by your analogy, we should still be able to survive with 4K of Ram.
I met a guy running Linux on his 486!! Correct me if I'm wrong but that's a 20 year-old machine. He did add some RAM (20Mb, that's the max it could take), and yeah, most graphical "goodies" couldn't run. But he had a pretty decent machine, that could browse the web, play music/videos, print/edit documents, spreadsheets, slideshows, ...
Microsoft aren't making enough efforts in that field (reducing requirements), and why should they? Everyone still blindly follows them. I'm glad to hear there's an improvement over Vista, but imho as long as they enjoy their monopoly, no real effort will be made on their part.
Computer manufacturers are happy with the situation, it gives their products a higher turnover, as the average lifespan of a regular computer is becoming shorter and shorter, with requirements getting more and more important. What will happen when Microsoft will stop its XP support (let's face it, it'll be in their interest) ? What will happen when programmers will stop developing programs for it? People will shift for 7, and most of them will need to buy a new computer to do so.
You say the world is evolving. True. But from what I see, forcing people to buy new hardware so they can have new software isn't evolution. Unless that new software could give new added-value features. And from what I see, 7 (as did Vista) is mainly about eye-candy. What could really motivate a satisfied XP user to pay 150$+ to switch to this "new" product? So unless we're talking about a massive breakthrough, I think that evolution should be focused on giving people the same power but with lighter, softer hardware. Less powerful hardware means cheaper hardware, which in turn means Internet access to millions of people who cannot afford it by today's standards. Think of Africa, and how difficult it is to give these people laptops running Vista (800$+/person ... some of them live with a 100$/year income ...).
I guess what I mean to say is that I don't see any good reason to buy 7. I don't know anything about it, but nowhere did I hear about one groundbreaking new feature that would justify the price (not to mention the hardware I should buy ... I have a 5 year old laptop ...). XP might be getting obsolete, (2 years from now it'll definitely be), and Vista is a failed experiment, so I foresee massive switching to this new product. Unfortunately.
Btw, I don't really feel concerned by the matter as I haven't used any Microsoft product for almost two years now. Not that I want to start a flame or anything, but think about it: with Linux being Open Source, there are no deadlines or commercial constraints whatsoever. People have the time (plenty of it actually) to try and optimize to code and lessen its requirements. Just a thought ...