I'm planning to order a Mac Pro and am wondering about two questions - grateful for any help! 1) I fancy an upgrade of the graphics card to the ATI 1900xt, but am hesitant, because its much higher power consumption than the stock model might increase the fan activity of the Mac Pro and thereby the noise level. I'd hate to have a loud system much more than having to live with somewhat slower graphics ... 2) About the RAM: the web page says that there are two bays of 4 slots. Is it important that the 4 slots on one bay are filled with the same memory size, or can one freely mix 512 M and 1 Gig sticks? Thanx!