Im worried about this, but I dont know if I should be?

Well it may be your HD spinning that you are hearing. As I don't have access to a G3 iPod I am speaking from experience of the original iPod and that is what it sounds like to me.
Now as to why it is - well does it restart the noise when you turn the hold switch off? Does it still whine when it goes to sleep ?

I wouldn't be too concerned at this stage.

It's normal. I have it. Others have it too.

I also have this noise on my 15 GB

I had this noise, too. But I don't think that this "is normal"! It's rather a construction error by Apple. I send in my iPod for repair and they gave me a new one. This new one had also the noise and now I get my money back. Instead I bought a G2 iPod.

My experiences with this noise are the following:

? ?Mosquito? sound appears more or less regularly when navigating through the menus or pressing a button.
? My experience told me that it especially occurs when the battery is not fully charged and when the background light is off. If you turn on the light, the sound is immediately gone.
? Sound appears even if the finger is close to the touchpad but not touching it.
? With the ongoing, continuous usage the sound becomes more and more permanent, even if you do not use the touch wheels and buttons.
? A total restore of the iPod does not fix the problem, but at first reduces it.
? This issue only occurs when the iPod is not connected to the Mac.
? Additionally: Sometimes the middle button is somewhat sluggish (for example when playing ?Solitaire?) and the touch wheel skips sometimes a menu entry.

So it is hard for me to believe that you all accept this. IMHO Apple made a construction error. The iPod is the most expensive MP3-Player in town and for me this is not bearable at all.

Just my 2 Euro-Cents.

Bender

Thats strange because i've just checked 15GB iPod and it
doesn't make any noise unless it's doing something.

Hmmm?

Your body heat activates the touch buttons. when you hold the ipod to your ear the 'whine' becomes even louder. Like everyone said, it's normal.

Originally posted by ZoidbergD
actually, it's the electric impulses generated by the body

Is the assumption right that the iPod works like a notebook trackpad? Well, my iBook is not making noise touching the pad. IMHO it is curious, that the noise appears when the batterypower is somewhat decreased. With fully charged battery the noise is gone, also with backlight on and connected Mac. Maybe it's an error in the control of the electric impulses? So why does this only happens under certain circumstances?

At least everybody must decide for himself if it's annoying or normal. For me, the iPod is an expensive high fidelity device in which every side noise is not acceptable. I got my money back so my case is closed. :-)