in my case, i have a dual monitor setup.
MC usually fills the whole screen on one monitor while I work/browse the net, etc. on the other.
what i'd like is to be able to work on one monitor and use the remote to control an unfocused MC on the other.
however, I believe i have found a work around using Girder that will initiate a macro when MC is not in focus. if you want to send a keystroke to an unfocused MC, girder will first bring MC to focus and then send the keystroke to the foreground window. if MC is already in focus, Girder will only send a keystroke. if you only want to send one of MC's core commands, Girder will just send a single send message command to MC.
while this sounds simple enough, getting there actually involved quite a bit of trial and error. the difficulty was mostly due to the fact that sending keystrokes to the main "Media Center.exe" window did not work. instead, i needed to send keystrokes to each and every Media Center child class and menu class, depending on which was in focus. in the end, a combo of macros, conditionals and sending keystrokes to the foreground window seemed to do the trick.
anyway, while not a perfect solution, i think i've got it working, but am still doing some tweaking before i post the GML file (hopefully this weekend).