MPD has been reported to run on a Pentium 75MHz CPU with 24MB of RAM. To get good performance from MPD, you probably want a Pentium 150 or 200MHz CPU. Also, if you want to run apache+ & phpMp on the same computer as MPD, then you probably want at least 32MB of RAM (you probably want more than 32MB of RAM, or you will need to tweak your apache configuration). MPD has also been run on ipod using flac files. So, there is no set in stone hardware requirements, and if you come to a computer that is slow enough to make it skip there are plenty of optimizations out there.