I've always used Windows Media Player, although I just bought an iPod, so I've needed to switch to iTunes for synchronization. I find that the interface is different, and it's taken a little getting used to (although I think I like it).

What program do you use most, and what do you like about it?

WMP, it's simple and intuitive enough for my needs.

I use WMP, MusicMatch, Sony ATRAC, and WACDDM.

I use WMP for streaming radio and watching video snippets, MusicMatch because it was recommended to me years ago as a good jukebox / mp3 library program and I've found no reason to stop using it, Sony ATRAC as I have a Sony MP3 player (although I only ever use it for transferring music to the player) and WACDDM which again I only use to transfer music to my Wi-Fi system.

I've never used WMP as a jukebox, so no comment on it really.

MusicMatch I like, but probably only because I'm used to it. I guess the thing I like most about it is that it has a wav / mp3 conversion utility. I know there are plenty of programs that do, but as I always have MusicMatch open, it's quite handy. Other than that, it's a fairly bog standard mp3 player / library. iTunes may well be better, but there's probably not much to choose between most of them - they all have to have the same basic functionality, so after that it's down to how pretty they look and whatever additional little features they have, neither of which is terribly important.

ATRAC is ok, compared to MusicMatch it seems to be pretty much featureless, but as I only use it for one purpose, which it does quite well, I've no complaints.

WACDDM is without doubt the shittiest, most horrible looking, featureless piece of badly written software I've ever encountered, but as I only use it for the one purpose, and it does this quite well, no major complaints.

VLC. Plays absolutely any video files under the sun.

Windows Media Player for the most part, just because it's the default player. But VLC will definitely play more different types of filesand have more codecs installed from already from the scratch installation onwards, so I need to use that as well once in a while.

On Linux, whatever I can get to play on Konqueror's own embedded features works for me. That or XINE. To be honest, sometimes I have to go through a bunch of programs to find the right one.

Windows Media Player, cuz that's the one that pops up first.

Windows Media Player. I tried using other programs, like Winamp, because they have cool skins. But Winamps buttons are too small and I usually have to spend several seconds staring at the screen trying to remember what does what. WMP is just more user friendly.