Imac G5 Fan Noise, hooking fw devices, inerfaces, HD Options

[camarao]

Hi,

I´ve ordered an Imac G5 1,8 17" with 2gb ram and a Lacie 200gb firewire disk and Logic Pro 7 .
I´ve read in the Apple discussion forums some big problems about the fan noise. It scared me because I want a silent computer ( I´m a PC user, you know...). I even heard the noise thru some audio files that were posted, and it was like a very, very annoying whine/buzz! It was terrible.
Yesterday I was to the store to pick up my Imac, but before paying and bringing it to home , I tried the Imac in the store and... there was that terrible noise! It´s not a very loud noise, but it´s very annoying, like a constant dentist drill... I didn´t brought it home! You have to wait a few minutes and you have to push the cpu to the limit to hear the noise. But after that the horrible sound is always there.
Meanwhile, I have a friend who has an Imac G5 20", and so I was running to his place to try the noise in his computer. The results : "quiet as a whisper" as Aplle claims. I´ve heard that this problem is more common in the 17" model.
So, I have some questions to you :

1- Did you heard about this ?
2 - Do you confirm that the noise is more common in the 17" model?
3- If I buy the 20" model, which has a 160gb disk, do you think I still need the Lacie firewire drive ( I will buy a M-Audio Audiophile Firewire ) ? Is the partition of the internal 160gb disk enough in terms of velocity power ( the space is enough for me) ?
4- Are there some kind of problems by having a firewire disk and a firewire soundcard in the same computer ( thru different connections) ?

I would appreciate your help, since this costs a lot of money and it´s a big decision for me ( it´s my first Mac).

Best vibes...