iPOD How many cds does it really Hold ?any Tips??

As stated above, it depends. If you store music uncompressed you can store about 70 albums. If you use Apple's loseless compression, then double that to 140 albums. The various AAC or MP3 formats can store even more.

I have the 40GB iPod with 5.4 days worth of music (1900 songs), the bulk of which are 320kbs VBR MP3's with some 128kbs and 256kbs MP3's as well as a few in Apple Lossless encoding, all of which uses only 12GB of capacity.

I primarily use it for air travel and I've found sound quality to be fine for that purpose. I use etymotic ER6 earphones (same idea as the Shure's) which work quite well for isolation on planes. Audiofranj is correct, you do hear body noises more clearly with earphones - the first time I ate an airplane pretzel with the etymotics in, I thought my head was exploding. However, I found the sound to be much better than Bose noise cancelling headphones supplied by American Airlines.

Ultimately, the question is what you are planning to use it for.

.
Ear phones for a plane ?
.
I would suggest the Sony noise canceling headphones - a bit bulky, but the best of the lot.
.
I owned the Sony liked them, read the Bose propaganda, bought the Bose, listened to them and then returned them. Sonics were not near as good as the Sony.
.
A friend suggested the ER6's, I then bought them. They were ok, but did not fit well into my ear, plus the sonics were not as good as the Sony. They went back in less than 3 days
.
Just bought the Shure e3c's, in addition to not being fun to have them stuck in your ear and listening to a pretzel being chewed, the sound was by far the worst of the entire group. They went back last week.
.
When I go on a plane or can handle the bulk of the Sony, I listen to the Sony. When I need something light weight when exercising or just don't want the bulk of the Sony, the Apple headphones sound are good enough.
.
Hope that helps
.

Apple Lossless and Sure E3c's for me. Make sure and try the different earpieces that come with the Sures. I didn't like the rubber tips, but the foam work great.
Steve

AAC files are actually smaller than MP 3 files, and are better quality. If you digitize your CD's using this compression method you should theoretically (depending on the length of songs you are digitizing) be able to store 10,000 songs on a 40 gig iPod. Apple lossless encoding is a different thing entirely, and is bit for bit an exact copy of your CD,