The UK Government reckons that servers with Linux installed are greener than those running Windows.

That's because, according to a report by the Department of Government Commerce about Open Source Software Trials in Government, open source software has lower hardware requirements and needs less frequent hardware refreshes.

In particular, it said that: "for equivalent open source and Microsoft Windows systems, the open source system will require less memory and a slower processor speed for the same functionality." It points out that Windows needs a hardware refresh every three to four years, while a Linux box might need a new platform as infrequently as every six to eight years - half as often.

The report continued: "Open Source operating systems such as Linux do not usually have the regular major upgrades that are a feature of Windows, and thus do not have the requirement that goes with these upgrades for a new or upgraded computer to run them."

The report then concludes that the reduction in hardware demands brings environmental benefits, because it translates into lower energy requirements and less waste, "reducing landfill requirements and costs arising from disposal of redundant equipment."

The report also coincides with Tory shadow chancellor George Osbourne's call for the use of more open source software in government. He said that the UK government could save in excess of £600 million a year if more open source software was deployed across various departments.

But if the timing of the report is good news for the open source community, it's possibly less welcome for others.

Microsoft Windows Vista has just been released to a flurry of criticism from environmental groups such as Greenpeace who slammed Microsoft for the hardware-hungriness of Vista, saying that upgraders will "will trigger a deluge of e-waste in developing countries.”

Beau Baconguis, Greenpeace's southeast Asia toxics campaigner, argued that: "With Vista, Microsoft could effectively hasten the obsolescence of half the world’s PCs, especially in the absence of fully-functioning global take back systems for PCs. Companies will feel the need to upgrade more computers sooner - and when they do, the world is unfortunately not prepared for the massive e-waste the upgrades will generate."

Greenpeace went on to argue that Microsoft should have considered this when producing its new OS.

It's a problem for which a solution will need to be found eventually. While most enterprises have few if any plans right now to move their desktops onto the new OS, most will eventually be forced to migrate as Microsoft starts to implement its phased withdrawal of support for Windows XP under its public life-cycle policy.

This is some way off, although the company has announced that the availability of licences for Windows XP Professional would be withdrawn for OEMs after 28 January 2008, and for system builders a year later. Mainstream support for XP Pro ends on 14 April 2009 while extended support - in other words, paid-for support - ends five years later.

Before that happens, Vista - or maybe even its more hardware-hungry successor - will have become the only commercial OS choice.