Remapping the Fn key in Windows * a solution *
If you own a Mac and you're running Windows via Boot Camp, it's likely that you've noticed that there are problems with the operation of the Fn key. Because the keyboard doesn't have a Delete key, it's extremely annoying that you can't use Fn+Backspace in order to get the Delete function.
As discussed in this thread it's possible to remap normal keys on your keyboard with a remapping tool like AutoHotKey. Unfortunately this application doesn't recognize the Fn key by default, so you're still stuck with other key combinations like Command+Backspace = Delete.
I don't use Boot Camp on my MacBook, but I do have a PC with Windows XP. I recently purchased an Apple Wireless Keyboard, which is basically identical to my MacBook keyboard. Using it in Windows is no problem, but the Fn and Eject key both don't work. So I suppose the problem is the same for users of Windows through Boot Camp.
First I used AutoHotKey to remap Command+Backspace to Delete. But I couldn't get over the fact that there were two keys that I couldn't use. So I kept looking for a solution, and finally found one. Using a DLL file for adding support for Human Interface Devices, written by one of the AHK forum members, I was able to get a response back from my Fn and Eject key. I wrote a script that let's you alter the behavior of the Fn key, so it will act as a modifier.
At this point my Fn key is fully functional, and I mapped all the basic OS X functions so they can be used in Windows. So whether I'm using Leopard on my MacBook or Windows on my PC, everything is the same. This means:
Fn+Backspace = Delete
Fn+F10 = Mute/Unmute
Fn+F11 = Volume Down
Fn+F12 = Volume Up
Eject key ejects my drive (without or with a delay just as in OS X)
And so forth.
Because the Fn key question is a common problem for a lot of people, I decided to write a full guide explaining every step of the way in full detail. The guide can be found right here:
Mystery of the Fn key - A guide to remapping the Fn key in Windows
The DLL used to retrieve information from the Fn and Eject key has already been used for many other purposes, and made it possible to map a lot of different keys on many different keyboards and other devices like mice and remote controls. By doing so it has proven its worth, and I'm sure that you'll be able to get your Fn key and other special keys working just fine. Whether it's on your Mac using Boot Camp, on a PC with using a keyboard with special hotkeys or on a PC notebook. The guide is based on remapping my Apple Wireless Keyboard, so at least I'm sure that it'll work for Apple keyboards.
Feedback on my guide and script and whether you succeeded remapping your Fn and Eject key is much appreciated.
Good luck!
MacBook C2D 2GHz, 2GB, 120GB, Mac OS X (10.5.2)