Once we tried Amazon to buy music Itunes will no longer have our business! Amazon mp3 is terrific! We had to do a short download of their software. That was very fast and took no time at all. Their selection of songs and albums to choose from is huge. We found their music easier to format to our different music players (mp3, mp4).
They also have tons of free songs you can download. Search those and you may find something terrific. I was surprised to find Trapt's newest song free.
Another big plus for Amazonmp3 is the price. Most songs are .89 compared to the .99 found at Itunes. Got to love more music for your money!

I have used Amazon.com for MP3 downloads via the Pepsi Points promotion.  I have had a few issues where the wrong song would download or the download would not come through all the way for me, but Amazon is quick to either fix the issue by allowing you to redownload the song or giving your account a credit.  Most of the time it goes through flawlessly.  It instantly uploads into your iTunes library too, with the song info and album cover.  It is almost too easy to use!  I actually like it better than iTunes or Rhapsody and would recommend it to everyone.

This year, AmazonMP3 has overtaken Apple's iTunes as my favorite online music store.  The main reason is simple: the files they sell are high bit-rate MP3s without any DRM.  My iPod and iTunes player can play them, but so can any other music player.  I don't have to worry about registering computers, or any of that nonsense.  Psychologically, it's also nice to buy from a store that doesn't treat you like a criminal. The integration with iTunes is basic (it just adds downloaded files to your library), but it works.  The storefront is about as good as the rest of Amazon, which is good but not as slick as the iTunes store.  An added bonus is that AmazonMP3 has regular special deals - one album per day is available from $1.99 to $3.99 and every Friday five albums are available for 5 bucks each.  The deals cover all genres, so my interest is hit or miss, but I've picked up some great new music that I wouldn't have looked at otherwise.