We usually tell by going to About->Information although that might not be your question. We realize that Windows XP/2000 comes built in with Windows Media Player 6.4 which can be run by typing mplayer2 in the start menu. Personally, 6.4 is all I use as I find all previous versions of Windows Media Player to be bloated. I don't listen to music using it, so I don't really need a playlist. It's the matter of watching a couple of movies here and there so it's quite sufficient.