And Opera.  Funnily enough, when we were doing the initial planning for our 3.0 platform I got some pushback from the dev team on this requirement because only .5% of our old site traffic was on a non-IE browser.  After we realized that they were serious we got the requirement straightened out, only changing it from "Mozilla" to "Firefox" since that's the predominant browser.  Installing the File Transfer Manager (FTM) still requires some effort, but a revision to the FTM client is in the near-term works that will address this and other problems.