I have an iPronto and have recently set up a PC with Windows XP MCE. I programmed the MCE remote control buttons into a screen on my iPronto and it works just fine.
The iPronto is just reproducing the IR control functionality of the MCE remote so I'm don't know how to answer your audio/video file type question. I have seen a thread in this forum that talks about the iPronto browser being used to remotely control the MCE PC via RealVNC, but the iPronto is not handling any of the MCE audio/video content as far as I know.
I borrowed an MCE keyboard and used it directly with my MCE PC. The mousing is achieved via a small stumpy rubber joystick in the top RHS corner of the keyboard (you press it down with your thumb and move it around). It worked OK but was not as fluid as a mouse. You do left and right clicks via keys on the top LHS corner of the keyboard.
I plan to borrow the keyboard again and program all the keys into my iPronto. My iPronto screen design skills are limited so it will be a very basic looking screen.
Note that all of this requires the MCE PC to have an IR receive capability. I have the OrigenAE X15e case, which came with an IRTrans module installed.
