School me on MP3 vs IPod

[topgunz1]

I rarely use my player in my ears, the only time I do is when I cut the grass and then you don't care if you can hear all the nuances, long as it can be heard over the mower!

 

[erazir]

Regardless of which device you use, I would stick with mp4 or another compression algorithm as opposed to mp3. The compression ratio of mp3 is better, but it shaves off frequencies that most people can't hear. However this does have an audible difference on the frequencies you do hear. Depending on the compression ratio you use, it can cut all frequencies below 60hz and above 15khz. I personally prefer the iPod and iTunes combination because of the hardware integration. It's very straight forward and easy to use when you aren't using pirated material. You just drop in a disc or drag over a file when you want to load it into your iPod and thats it. It's not the best solution but it is far from the worst.
As far as in ear monitors, the best I've found are future sonic. I love mine but they are too expensive. I'd lean toward Shure, audio technica or sennheiser and avoid m-audio/avid.
Regardless, a portable media player is a great device to own as you can consolidate all of your music and bring it with you for most activities.