Microsoft set out to adopt a formal and rigid support lifecycle in 2002, back at a time when most analysts were expecting to see Windows Vista (then, "Longhorn") within a couple of years. My own point of view was that this lifecycle business had a lot to do with Microsoft's then-new volume licensing scheme, which among other things is oriented towards selling software subscriptions. If you're buying a subscription for software, you can see how lifecycle plans become important. However, delays in Windows Vista coupled with a questionable approach to "consumer" products means that 2007 will carry a few surprises unless policy changes are made at Redmond.

XP Professional and Home are divided into two general product categories for Microsoft, namely business and consumer products. XP Professional, as a business product, will receive mainstream support for two additional years after the release of Windows Vista (whenever that may be). After that, Professional will have an additional five years of extended service (minimum), though this could be lengthened considerably if the OS update after Windows Vista does not ship within three years of Vista's debut.

Mainstream and Extended support are virtually identical, with both carrying security updates, service packs, online support, and the availability of paid support. However, the transition to the Extended Support phase means that hotfixes that are not security related will be made available by a (paid) commercial contract, warranty claims can no longer be made, and Microsoft will not entertain adding any new features or design elements to the OS.

Based on the current timeline and our own expectations for the launch of Windows Vista, we estimate Windows XP Professional Mainstream Support ending in late December 2008, with Extended Support ending in December of 2013. It could stretch out longer, but we don't expect the window to be more than two to three additional years. After the Extended Support phase is finished, online support (knowledge base, FAQ, etc.) will continue for 10 years.

Windows XP Home coming up short

Windows XP Home is another story. As a consumer product, it suffers from two policy deficiencies. First, consumer products do not qualify for Extended Support, but instead move directly into the online support phase after Mainstream Support ends. Second, whereas business products are guaranteed Mainstream Support for two years beyond the release of the next subsequent version of a product (in this case, Windows Vista), consumer products do not get this built-in transitional period. The end result is that Windows XP Home will leave Mainstream Support and enter online support on January 1, 2007in less than a year.

When that day comes, XP Home users may feel left out in the cold, because they will no longer qualify for security updates, and will not be able to purchase support from Microsoft. Finding this situation somewhat alarming, I contacted Microsoft's representation to clarify the matter. A Microsoft spokesman relayed the following to me:

"For consumer products, security updates will be available through the end of the mainstream phase. For Windows XP Home Edition, there will be no security updates after 12/31/06." Regarding paid support for problems unrelated to security patches, I was told that "Users who want to continue to receive support after the Microsoft assisted and paid support offerings have ended may visit the Retired Product Support Options Web site."

I urge Microsoft to reconsider this stance. There should be considerably more overlap in support for their consumer OS. While five years of support for XP Home may have seemed reasonable when it was expected that there would be little more than three years between major OS updates, the time it has taken to bake Windows Vista has thrown this out entirely. If Vista launches in October, it would give users a mere two months to move to the OS, or risk being unsupported.

I suspect that Microsoft will grant a stay of execution for Windows XP Home, because the alternative is to create a PR nightmare that would also leave customers fuming. Citing emerging markets in the past, Microsoft extended support for Windows 98 and ME by more than two years, and this decision was made long after Windows XP was released. Microsoft should extend support for Windows XP Home well into 2008. Otherwise users will have to hope that updates to XP Professional meet their needs, but it remains unclear if Windows Update will point XP Home users to updates to XP Professional.

Update: Support has been quietly extended.