Prelude:
As of June 2004, Microsoft has defined a time line for the life cycle of their products. That includes the Windows operating system, as well as their applications. Check out these links...

- Microsoft Support Lifecycle Policy FAQ

- Select a Microsoft Product for Lifecycle Information

- Microsoft Windows Desktop Lifecycle Policy

What Is The Time Frame?
With some exceptions for earlier operating systems and applications, Microsoft products become obsolete roughly 5 years after being released. That means Microsoft stops making it available after being out for 5 years. And, they basically stop supporting it after that. There are some exceptions where Microsoft will support a "Business & Developer" class of software for as long as 10 years. But, this really is support as it existed when Microsoft stopped making it available, which is the 5 year mark. And, most of that support is online documentation for self-help. This will satisfy most government and military product support criteria. But, this is not realistic in today's Internet and network connected environments.

If I Bought The Software. I Can Use It Forever... Right ?
Well, yes. That is true. And, if all things were equal, there would be no issue with that. The issue is that software companies need to keep upgrading and periodically releasing newer versions of their product to stay in business.
. One of the advantages is that they can add features that may be wanted by users. Another is that bugs can be corrected, although most interim updates are typically supplied at no charge.
. But, there is another thing that tends to happen, which can be negative to users that don't upgrade. The file formats sometimes change. After a few iterations, many software developers will drop older file formats, making it impossible to open older versions, or saving as older versions. Mostly, users of older versions will not be able to open default file types of files saved with the newer versions.
. In larger offices with many users, machines get added or replaced, all the time. And, there is an increased instance of users with newer systems that will save and send files to users with older systems that cannot open them. So, there will always be pressure to keep upgrading older systems, in this scenario.
. Another thing to consider with aging operating systems is their ability to safely exist on a network or the Internet. With the prevalence of malware, operating systems will continually need periodic patches and updates to remain secure. Utilizing an obsolete operating system means this support is not available.

How Can they Get Away With That?
Industry and technology has created the scenario of obsoleting hardware and software. Just think of what kind of computer was available 5 years ago. Hardware keeps evolving, getting faster and doing more things. And, software is being developed to take advantage of the advancing hardware capabilities. After a few iterations, the newer operating system becomes too large and complex to load onto the older system. And, driver support for older hardware will probably not be supported on the newer operating system.
. These advances would not happen if demand wasn't there, either by the consumer or professional market. As the end user expands and grows their computer capabilities, they continually progress to the limits of that system.
. Another factor contributing to system obsolescence is that manufacturers of hardware will stop manufacturing and supporting the older hardware as they keep creating newer products. It isn't practical to support that kind of inventory.
. All these things help to create the probability that a system will need to be replaced, either by inadequacy or inability to maintain. No matter when a system is purchased, it is in the process of becoming obsolete. Within 5 years of its creation, most computers are not capable of supporting the user's current needs. Or, it becomes impractical to keep operational.

Has this Always Been Going On?
Since the invention and inception of computing, there has always been a constant effort to make it "better". To date, it has never been at a point where society has thought that it was adequate for everything. Some things, like word processing, don't require a lot of computer power to do. But, creating a complete book, fully paginated with illustrations could not have been easily done until recently. High resolution digital photography and video production had barely become feasible to the average home user around the year 2000. Just imagine what will be possible on a personal computer in five more years...

A Couple More Interesting Links...
. Check out these links showing the recent progression of software and hardware...

- Microsoft Windows Desktop Timeline

- Intel Microprocessor Quick Reference Guide