From CNet News:
Microsoft has drawn some criticism after confirming that it will not make the next version of Internet Explorer available to users of its Windows 2000 operating system.
In a blog posting at the end of last week, a Microsoft employee confirmed that the company would not be releasing IE 7 for Windows 2000, as this would involve a lot of work for an operating system that is in the later stages of its lifecycle.
“It should be no surprise that we do not plan on releasing IE 7 for Windows 2000. One reason is where we are in the Windows 2000 lifecycle. Another is that some of the security work in IE 7 relies on operating system functionality in XP SP2 that is non-trivial to port back to Windows 2000,” according to the blog posting.