Terry Maguire, MD of Computer Remarketing Services, which specialises in the recycling of IT equipment, has highlighted specifically the impact of legislation resulting from the Waste Electrical and Electronic Equipment (WEEE) directive.

He claimed that the real cost of launching the new OS will come in the form of the safe disposal of legacy systems that can't run Vista. It's a cost that will be passed onto thousands of other businesses when the laws come into force, in July of this year.

'Not only are the indications showing hardware upgrades will be a necessity in most circumstances,' said Maguire, 'but the WEEE directive legislation clearly states that 'producers' of any electronic waste are to pay for the safe disposal and treatment of their own waste. However, Microsoft will not be paying into any compliance schemes and are not required to pay a penny towards the recycling of old IT equipment, or the potential effect on the environment.'

The subject of Vista's environmental impact has been rumbling on since its launch earlier this week, with the Green Party doing its best to rain on the parade.

The political party has decried the arrival of Vista as doing more harm than good, with the inevitable encouragement for people to upgrade their hardware. Irrespective of the fact that Vista may only require extra RAM plugging in, the party urged users to turn instead towards equivalent free software, such as Open Office.

Vista requires more expensive and energy-hungry hardware, passing the cost on to consumers and the environment,' said Derek Wall, one of the party's two principal speakers.

'This will also further exclude the poor from the latest technology, and impose burdensome costs on small and medium businesses who will be forced to enter another expensive upgrade cycle.'

Microsoft was quick to respond, defending its green credentials and highlighting power saving aspects of Vista, even if these just consist of sleep or hybrid sleep modes, or relying on the processors running the computer to have power management features allowing the chip to run at a lower rate when idle.

'Environmental stewardship is important to Microsoft,' insisted company spokesperson Matt Lambert. 'We are actively involved in PC refurbishment and computer recycling programmes that send unwanted PC's to those who need, but can least afford them.'

He also maintained that Microsoft had addressed concerns about power consumption: 'We also developed Windows Vista in a way that promotes energy conservation - reducing both enterprise and consumer energy bills as well as the harmful environmental impact from electricity generation.'

For its part, the UK charity Computer Aid International has also flagged its concerns over the new operating system.

'There may be as many as 10 million PCs discarded in the next two years as they are replaced by Vista-compatible hardware,' said the charity's CEO, Tony Roberts.'We are urging individuals and businesses to consider the environmental impact of those old machines, many of which will still be in perfect working order.'

'And we are reminding them that re-use is the best option for the environment. Choosing re-use over recycling allows IT equipment to be used until the real end of its productive life, enabling individuals and businesses to reduce their environmental footprint.'

'Only when a piece of IT equipment is no longer of use should it be broken down,' he stressed.