I saw this as I was downloading Firefox for Windows XP (running in Parallels Workstation on my Intel mini). Needless to say, given the horror stories I'd heard about Windows' security, my first thought was 'my XP box has been hacked!' A bit of research, though, proved that this is a legit Firefox mirror...albeit one that may cause issues for those downloading from, say, government agencies, large companies, or anyone else likely to have an Internet filtering solution in place.
BTW, if you have an Intel-powered Mac, do yourself a favor and check out Parallels--it's really pretty amazing being able to run any number of guest operating systems at near-native speeds, all within the friendly confines of OS X. I wrote about my experiences with it for a recent Macworld piece, and included a video that shows XP's speed on the Core Duo mini. Today's release of Parallels beta5 included basic USB device support (flash drives only for now), as well as the beginnings of a nice shared folder solution for sharing data with the host OS X machine.