@predatorftp: I've been playing with the original MS remote on standard XP but using the drivers from XP Media Center edition.
I put the remote on a nice clean freshly installed system to avoid any complications. I found that the MS remote does not send keystrokes for many buttons, and it doesn't send the "standard" keystrokes for many others.
With Windows Media Center Edition there is a set of standard keys e.g. ctrl-shift-P means "play". All the clone remotes I've looked at simply emulate a keyboard and send these standard keystrokes. Working this way means they don't require any drivers because Windows just thinks they're a USB keyboard; plug them in and they just work.
The pukka MS remote *does not* work this way. When I plugged the receiver into my test XP setup I got a "hardware cannot be installed error". I had to install separate drivers (that I got from the Windows MCE rollup2 hotfix). Having done this I did get an extra keyboard device, but as I said above it sends different keystrokes to my clone remotes.
I assume MS have designed their remote to work with MCE directly via the IR rather than just by sending keystrokes. In that case I can't make XBMC work with it because my mods just process keystrokes. It looks as if you're better off with a cheap clone remote than with the real MS remote :-(
One last comment: have a look at
http://forum.xbmc.org/showthread.php?tid=61571. This describes how to make the MCE remote send whatever keystrokes you want. I tried it, and it does work. However it's quite a complicated procedure and not for the faint hearted, and I don't know if it would break anything else. If it's of interest I might be able to come up with a config that makes the MCE remote emulate the clone remotes that are, err, emulating the MS remote :-)
JR