Microsoft's support runs in three phases - mainstream, extended, and self-help, which you can see here.
Mainstream support for Windows XP Professional ended in April while extended support will stop in April 2014 - eight years and 13 years after the operating system shipped, respectively.
This is one of the longest support cycles that Microsoft has given an operating system and is a comment on Windows XP's ubiquity and the failure of Windows Vista to take off, rather than Microsoft's own largesse.
Typically, extended support ends around seven to eight years and you should expect this to become the norm once more, if adoption of Windows 7 kicks in it does what Windows Vista failed to achieve - displace Windows XP.
The other issue the FSF could find traction with is Microsoft's SKU policy. Windows 7 will come in six versions, each priced differently and with features intended to target what Microsoft perceives as different sets of customers. The logic is simple though: the more you pay, the more features you will get.
But the features list is curious: There are just two differences between Windows 7 Professional and Ultimate - the former lacks BitLocker data encryption and the ability to switch between 35 languages. Windows 7 Enterprise, meanwhile, will also offer BitLocker but only be available to customers under Microsoft's volume licensing program.
There may be just two differences between Windows 7 Professional and Ultimate, but the former is priced $199.99 for an upgrade edition and $299.99 new, while the latter is $199.99 for an upgrade copy and $319.99 for a new version of the software. Enterprise customers: It's down to you, your Microsoft rep, and the strength of your negotiating skills.
Letter from history
The FSF has drawn a parallel between the new operating system and Windows NT Server and Windows NT Workstation 4.0 in the early 1990s.
Infamously, Microsoft insisted there was a great deal of difference between these two operating systems, but analysis proved they shared the same kernel. The real difference was in the fact Windows NT Workstation limited the number of IP connections a machine could make to 10 - a limit Microsoft introduced after Windows NT 3.5.
The idea was to stop people putting Windows NT Workstation on their servers, and encourage them to buy the more expensive Windows NT Server priced around $1,000 for this instead.
With many Linuxes you get one version for the desktop and one for the server.
In its letter, the FSF tried to wrap up its seven points, but it might just as well have focused on two - support and pricing - as the penalty of buying into Microsoft's closed-source roadmap.
"Replacing all your desktop systems with GNU/Linux will give you independence from Microsoft, access to thousands of free software applications, and help break the social ill of proprietary software. Thousands of organizations have already moved to free software. What's your organization's plan?
"Investing in Microsoft's Windows 7 will only get you more stuck and more dependent on them," the group said. ®