XP is 1 Year Old (In Dog Years)

Seven years is a mighty long for an operating system to hang around. But PC users still clamour for Windows XP even a year after the upgraded - and initially buggy - Vista OS was released. But Microsoft says enough is enough...kind of.

Today is the last day that Windows XP will be available for widespread sale. Retailers will have only until their current supply is exhausted to sell boxed copies of the operating system.

Although XP will disappear as an option for most computer buyers, the operating system will live on in several key ways:

• XP will be available on PCs from smaller computer makers known as "system builders" until January 31, 2009.

• XP will be available for so-called ultra-low-cost-PCs until June 30, 2010.

• The low-end Windows XP Starter Edition will continue to be available in emerging markets until June 30, 2010.

• Windows Vista Ultimate and Windows Vista Business come with downgrade rights. Some computer makers are using this option to offer machines that appear as Windows XP products but are "factory downgraded" to XP. The downside is that only pricier versions of Vista qualify, but the benefit is that the machines come with the option to eventually move to Vista for no added fee. Microsoft says it will continue to make XP discs available to computer makers to enable downgrade rights through at least January 31, 2009.

• Microsoft is not ending support for Windows XP. Mainstream support continues until 2009, while extended support is not due to end until April 2014.

Meanwhile, Apple has released Mac OS X 10.5.4, the fourth update to Leopard since it was released last October.

The new version contains the usual mix of bug fixes and security updates, with iCal getting the most attention. iCal won't delete events without telling you as a result of the latest update, for example, and Apple said the update "improves overall iCal reliability." Airport and Spaces & Expose also received some updates.