do I need special software for the MPx or can I install old software build for the "old" PPC's like Dells X50 or Toshiba e800.
To answer your question...YES, this phone will run most windows based software from 3rd party vendors ie. games, videos, etc., however, I would not download any software that would compromise the main operating system on the Flash RAM of this phone.
Do it at your own risk!!
Hope this info helps.