Bill Veghte, Microsoft's senior vice president of Online Services & Windows Business Group, has written a letter addressed to "Windows Customers" in which he explains his company's plans around the operating system that powers "more than 1 billion personal computers around the world." In the letter, he talks about Windows XP, Windows Vista, and the upcoming Windows 7. Most of what he says has already been announced, has been gathered from various sources, or has been speculated based on hints from Microsoft employees. Nevertheless, it's great to see the facts all in one place, and straight from the Microsoft's mouth. Here is a quick rundown on the key points from the letter, without any of the PR malarkey:

Windows XP's "end of sales" date is still June 30, 2008. After this date, XP cannot come preloaded on a new computer without the purchase of Vista, nor can it be purchased in retail.

XP Professional will be available with the purchase of Vista Business or Vista Ultimate. This option from Microsoft is known as "downgrade rights" and essentially lets you legally use XP on your new PC, and move to Vista when you are ready without having to pay for an upgrade. OEMs have already said they will support this.

XP Home and XP Starter will still be available on budget systems such as ULPCs.

System Builders will be able to purchase XP through Authorized Distributors until January 31, 2009.

Security updates and other critical updates for Windows XP will continue until April, 2014.

As shown in a Microsoft report, Vista had half the number of critical vulnerabilities as XP SP2 did during 2007. PCs running Windows Vista were 60 percent less likely to be infected by malware than those running Windows XP Service Pack 2.

Vista currently supports about 77,000 components and devices. This is twice as many as supported at launch, meaning that Vista's compatibility has significantly improved. It looks like Ballmer's quote of calling Vista a "work in progress" has a kernel of truth.

98 of the top 100 applications for Windows sold at retail in US in the last year in the categories of Finance, Business, System Utilities, Imaging/Graphics, Personal Productivity, and Education, are compatible with Vista.

Application Compatibility Updates, installed automatically through Windows Update, enable more than 125 popular PC games to work on Vista.

When compared to Vista RTM, Vista SP1 copies files up to 50 percent more quickly and decompresses contents of a large folder 71 percent faster.

Customers have told Microsoft they want broader support for devices and applications and so, Windows 7 will be based on Vista.

Microsoft plans to deliver Windows 7 approximately 3 years after the January 2007 general availability launch date of Windows Vista. For those who need it said again, that means after 2009.

Veghte also took the opportunity to emphasize that Vista is better than XP, but regardless of the user's choice, he said that Microsoft strongly recommends the installation of the latest service pack. Hopefully this quick rundown clarifies a lot of misconceptions around XP, Vista, and 7; thank you Veghte for taking the time to keep us customers in the loop.

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