First, a reminder of just what is iTunes Plus. The original versions of songs and videos on the iTunes Store were all hindered by copy protection (DRM). The songs and the audio portions of videos were all encoded in 128 kbps AAC. AAC is a newer and better sounding audio encoding standard that was developed by some of the same people that developed the older MP3 coding standard. iTunes Plus changes both of those aspects for the better.

The FairPlay DRM that Apple uses is not a part of an iTunes Plus file. As a result, there are no technical barriers to run into if you want to listen to your music in an “unsanctioned” way . So, if you have a car stereo that can play AAC files you’ll be able to do that with songs you bought from the iTunes Store in addition to songs you imported from your own CD collection. You can also listen to iTunes Plus songs on any cell phone that can play AAC such as the Nokia N85. All of the major game consoles (Nintendo Wii, Microsoft Xbox 360, and Sony PlayStation 3) will play iTunes Plus songs but will not play any iTunes Store songs that are protected with FairPlay. Finally, most non-iPod music players also support AAC as well and will play iTunes Plus music. There are probably other uses you might run into where DRM will stop you – but with iTunes Plus there are no worries!

The second enhancement that iTunes Plus brings is higher fidelity. Each song (and audio on videos) is encoded as 256 kbps AAC. That means twice as much data is used every second to represent the sound and that you’ll hear more detail of the original recording.

What To Do

With that out of the way, it gets easy. Simply launch iTunes and select the iTunes Store from the list on the left. You’ll have an option to upgrade your library to iTunes Plus on the top right of the screen in the Quick Links section. Unfortunately, it is all or nothing. So, take a look at the total fee that Apple calculates and feel free to preview any of the songs that iTunes found to upgrade before making your decision.

Also, don’t forget to check back in the coming weeks as more and more songs are available in iTunes Plus. On the day of this announcement there were 8 million iTunes Plus songs available. But, Apple expects to have all of its songs, an additional 2 million worth, available as iTunes Plus by the end of March.

Update: You can now select individual songs and music videos that you want to upgrade. Previously you had to upgrade all of the items they have available in iTunes Plus.