True, Microsoft and vendors do have contractual agreements on how they can sell software.

I think the telling point is that the manufacturers asked to keep shipping XP. I understand their reasons, but no one is forcing anyone to do anything here.

Customers do not have to purchase machines from vendors with an operating system.

Vendors do not have to sell XP, though they do (for valid reasons).

Microsoft doesn't have to offer XP at all, but they have business reasons to sell newer versions of their software - additional/improved features, increased stability, etc.

Yes, I agree that Vista isn't better than XP in a lot of areas, but Microsoft developed a newer version of their operating system in the somewhat misplaced belief it was better.

At the end of the day, no one forced anyone to do anything here. Dell/Lenovo/HP did not have a gun put to their head to sell XP. They decided to do that themselves and they must accept the costs involved with that business decision.

Lastly, I will say that I find it disagreeable that Microsoft would include language and provisions that would require the vendor to purchase two licenses (XP and Vista) when only one would be used (XP). Microsoft made a business decision to deter people from sticking with their previous operating system which the vendors accepted. Personally, I don't think they did anything legally wrong... just morally. I suppose that's just one of many reasons why I'm not running Microsoft.

Actually, the cost isn't the same.

For every new computer model (new/upgraded parts and versions of drivers), computer manufactures test the builds. This means that, as opposed to testing and certifying Vista with the NVidia 9800 card, they have to certify the machine with XP. This does add additional cost and time before they can sell it. Multiply this one factor over every component they offer and the cost does become very high. To use your example: It may be zero cost in storage once the engine is developed, but in this case - the cost to redevelop and test the engine every time a new spark plug model comes out isn't zero cost.

After that, add additional support costs for personnel as supporting multiple operating versions with vastly different quirks (I'm talking about Vista here) and you incur even more overhead.

Support organizations tend to prefer a single or at least uniform support model for individual products when possible to limit overall costs. Assuming that there are two groups to support the different operating systems (some for Vista and some for XP), having a single person out of one group makes support times longer and raises costs because you need to then keep even more people staffed to cover employees who aren't able to work (sickness/vacation/whatever).

True, there will be some people who can support both products, but not every support shop has a phone queue that can or will have some people in the queue for XP, some for Vista support, and some that can do both. A separation of expertise is sometimes very useful as the people who focus on a single product become better able to support that one product over time. Take the finance person in an office who can't change their windows resolution, but can tell you the most obscure piece of information about Excel. They focused on a single product and became experts at it.

What I'm saying is... there isn't a zero cost involved here.

That's just it. Your life is NOT threatened. Your *way* of life is threatened.