This has got to be among the simplest possible things in the word for those who know how to do it. However, I don't, and I have been astonished to find nothing about it from google searches other than unanswered copies of the exact same question.
All I want is Firefox, and I want it for all users on a Windows 7 laptop. In fact, the real story is that I want it to work again for all users after updating from Firefox 5 to Firefox 8, which process has apparently left it unavailable to anybody but the administrator.
I'll probably find the answer to this in the time it takes for this question to get answered, but I promise I'll upvote you anyway :-) I mainly wanted to get this question (hopefully with good answers) out there so that it turns up on a Google search.