Microsoft's new Zune media player, which goes on sale today, is aimed directly at Apple's wildly successful, music industry-changing iPod. But how does it stack up?

The main innovation is WiFi-based sharing of songs and digital photos wirelessly between two or more nearby Zunes. There's also an integrated FM radio tuner, something the iPod lacks. The display of the Zune is bigger, and the screen automatically shifts to a wide, horizontal view for videos and pictures.

Battery life of the Zune is about the same as the video iPod, as is the cost (the Zune costs $250. A comparable 30GB iPod with video costs $249) The Zune Marketplace uses a point system in which most songs cost 79 Microsoft Points each - the equivalent of 99 cents - the same that iTunes charges for most songs.

Microsoft explains that this Zune is just the first of what will be an entire family of media devices. Will the Zune eventually become a Voice Over IP phone? Will it be able to download music wirelessly from the Zune Marketplace? Will smaller, flash memory-based Zunes -or Zunes with larger storage capacity emerge any time soon? Only Microsoft knows. For now, though, the questions are: Should you buy a Zune? Should you switch from an iPod?

I've been testing a couple of Zunes along with the online Zune Marketplace, Microsoft's answer to Apple's iTunes music and video store. Here is how I think they measure up against Apple.