MDJ has a dead-on assessment in today's issue of how Microsoft is seeking to co-op the online music market:

Nonetheless, even more companies are jumping into the fray, helping Microsoft's attempts to portray its completely proprietary and highly-restrictive Windows Media format as "standard" and QuickTime as "proprietary."

[...]

The proliferation of "music stores" pleases Microsoft greatly. The company wants to point to about a hundred different services, all selling songs at US$0.99 each, and say that 9 of them use Windows Media and only one does not - iTunes Music Store. This is how new monopolies are born, and Microsoft doesn't even seem to be leveraging Windows to do it. The company simply added capabilities for highly restrictive and revocable rights into Windows Media, and content creators are flocking to it, pleased at being able to keep purchasers from using their songs or video how they please. Fortunately, Apple has all the bulk of the mindshare right now when it comes to buying music online. Magazines, polls, sites, et al are lining up to declare the iTunes Music Store or the iPod as product of the year, or including them in some sort of Top 10/20/50/100 list. Not to mention that while files downloaded from the iTMS do contain a form of digital rights management (DRM), said form isn't anywhere near as restrictive as that of the Windows Media format. Not to mention that what some of the other online music services are peddling are nothing more than revamped subscription formats. People who buy digital music don't want to subscribe to it. They want to buy it, download it, pop it in to a MP3 player, burn it to a CD, and get on with their lives. They don't want to keep paying for the same song again and again. This is the life those services trumpeting WMA are trying to lock consumers in to. Personally, I haven't bought anything from the iTunes Music Store. I like my CDs, with a physical item that contains the mastered AIFF files. I like my liner notes. I like being able to rip my CDs at any rate I wish, rather than have to take the rate an online service delivers in. The dirty secret of the iTMS is that you can pay just a couple of bucks more for a full album from Amazon and get all of that. Michael and I have had variations of this conversation on more than one occasion, and he is of like mind. That said, if I were an online music buying fiend, there is no doubt it would all be from the iTunes Music Store. Best selection, even if it's not complete. For a DRM system, it's pretty fair. Quite simply, it's the best, Chairman Gates can't stomach that, and Matt D. & company take Microsoft to task over it.