I would not recommend buying music from iTunes.  Most iTunes music contains (or used to contain) DRM or Digital Rights Management which means the file itself contains code limiting the access you have.  In laymens terms, if you buy songs with DRM then you'll be limited on what you can do with it.  In the case of iTunes it limits the number of times you can burn a song to CD and prevents you from playing it in other media players.

The most popular place to buy DRM-free music is Amazon.com

Here is a link:

http://www.amazon.com/MP3-Music-Download/b?ie=UTF8&node=163856011

You can download songs for about $1 each and full albums for around $10.  The prices vary based on the music's popularity or current deals they are running.

I'm not an iPod user, and I've never tried iTunes, so I can't comment on that service. I've used Napster (www.napster.com); I think downloads are about $1 each and they have all kinds of music available.

If you like indie and old school music, there's a membership service called emusic (www.emusic.com). you pay a fee each month and receive a certain number of dowloads. The plan I'm on is about $11/month for about 20 downloads. But beware, they don't have a lot of the "Top 40" artists; their focus is on smaller record labels, though they've recently expanded to include some classic rock acts (Led Zeppelin, Journey).

Hope this helps!

Limewire has been given a court order and is now shut down.. I have however started using frostwire, great selection and easy to find songs. no cost at all.. all though it may be getting shut down too.

I would strongly suggest that you visit the run2rhythm running music website at www.run2r.com

It has specially composed music for running and is an excellent training aid.

Dave

There are tons of free music podcasts available on itunes. I like Indie Feed electronica and Heaven's lounge. Great Running music.