I am pretty happy with iTunes on my Mac. However, I am not nearly as satisfied with Windows Media Player or the Zune Player when I am using a PC running Windows. I noticed that the first release candidate for the Mozilla Songbird project was released a few days ago...

Songbird 0.7 Release Candidate 1 is Available for Testing

So, I downloaded and installed it on a Windows XP SP1 PC. It is not as pretty as Windows Media Player, Zune Player, or iTunes. But, it certainly seems functional. I found it easier to find and play selections on Songbird as compared to WMP or the Zune Player (which also issued errors everytime I use it). Songbird seems to have a small but noticeable delay when I click an item to play. But, it is not long enough to be irritating (so far). This one is staying on my PC for the moment.