At the website Windows7Sins.org, the FSF lists the seven 'sins' that proprietary software such as Windows 7 commits against computer users.
They include: Poisoning education, locking in users, abusing standards such as OpenDocument Format (ODF), leveraging monopolistic behavior, threatening user security, enforcing Digital Rights Management (DRM) at the request of entertainment companies concerned about movie and music piracy, and invading your privacy.
"Windows, for some time now, has really been a DRM platform, restricting you from making copies of digital files," said executive director Peter Brown.
And if Microsoft's Trusted Computing technology were fully implemented the way the company would like, the vendor would have "malicious and really complete control over your computer".
The result is that Microsoft could do things like Amazon, which last month went into customers' Kindle e-readers and deleted illegally-sold copies of novels such as George Orwell's 1984, he said.
"This is treacherous computing," Brown said.
Microsoft did not immediately respond to a request for comment.
The group, best-known for overseeing the General Public License (GPL) used by most open-source software, including Linux , also plans unveil a 12-foot-tall art installation depicting Windows 7 "being trashed", in Boston. The FSF also said it will send letters to top US companies arguing that they would benefit ethically, technically and, in the long-term, financially, from switching away from Windows and Microsoft Office to free alternatives such as Linux and OpenOffice.org.
Founded in the mid-1980s by hacker-activist Richard Stallman , the FSF argues that free software and source code is a moral right. It takes pains to distinguish itself from the open-source movement, which advocates sharing of source code but tolerates charging for software.
Even with DRM, users running Windows PCs still maintain more freedom and privacy than those who foolishly use cloud computing services such as Google Docs and store their data there.
"That is the ultimate giving-away of your freedom," he said. "That's not a software freedom issue, it's a stupidity issue."
"Large corporations spend an awful lot of money on software. They face numerous software audits and more vendor lock-in than you or me," Brown said. "I'm not expecting an instant wave of companies switching off XP to Linux," he said. "But we would like get that debate going. Hopefully, some will re-evaluate and say no to Windows 7."