The Free Software Foundation (FSF) is holding a rally in Boston, Massachusetts today to campaign against Microsoft and proprietary software, ahead of the release of Windows 7 on 22 October.

The FSF was founded in 1985 to promote the use of free software, particularly GNU operating software and its GNU/Linux variants, and the rights of users to modify and redistribute computer programs.

A Windows 7 Sins campaign outlines seven areas where the FSF claims that proprietary software can hurt users - invading privacy, poisoning education, locking users in, abusing standards, leveraging monopolistic behaviour, enforcing digital rights management, and threatening user security.

The points are outlined in a letter sent to the heads of every company in the Fortune 500, except Microsoft.

"Our growing dependence on computers and software requires our society to re-evaluate its obsession with proprietary software that spies on citizens' activities and limits their freedom to be in control of their computing," said FSF executive director Peter Brown.

"Our national and local governments, non-governmental organisations, universities and schools that use proprietary software are undertaking bad public policy, often through ignorance or misplaced values.

"There is free software available right now for any activity you or your business needs, and it is better in the most important aspect: it respects your freedom."

Matt Lee, manager of the new FSF campaign, hopes to make businesses and computer users more aware of what he perceives as the growing dangers of proprietary software from Microsoft and companies such as Apple and Adobe.

"With the release of Microsoft's updated operating system, business leaders have the opportunity to escape to freedom and join a growing list of leaders who understand that sinking money and time into proprietary software is a dead-end inconsistent with their best interests," he said.

Microsoft could not immediately provide comment.