Amazon's MP3 service are DRM-free MP3s that can play on any machine. Their download software will even install your music onto iTunes for you. iTune's are more specific to an iPod and are about $0.30 more expensive per song! That means you'll save $3.00 on a 10-song purchase! Most of the songs are the same on both groups, so why not pay less?
I prefer to work out in the mornings, but that's also when I prefer to have my quiet times, since the kids aren't up yet. Here's a way to combine the two: LISTEN to scripture while working out. I play the audio files on my iPhone while I'm on the Elliptical, praying before/after while stretching/cooling down. This gives me the spiritual and physical charges I need each morning. No matter what the day holds, I know that I started it out right!
I'm going on vacation tomorrow, and since I won't be able to watch my favorite DVD to workout each day, I used my computer to copy the audio as an MP3 that I am adding to my itunes library. I've seen the video tons of times, so I will be able to get through the workout without actually seeing it!
Go through all the songs you have on your computer and pick out ones that make you want to lipsync and dance around the room (since they're so much fun). Make a playlist containing those songs and play those while you workout. Don't stop there, keep that list up to date so you don't get bored.