Woops, sorry about the 3rd part. I turn the computer off each day, so i turned it on this morning, put it into standbye, then have been using it for about 2 hours now. When i quit iTunes, it doesn't immediately get up to 100%, but after about 15mins of playing it gets right back up there.
Weaselboy, yes i have iTunes Genius and Push turned off. iTunes honestly has always done this to me, generally 400-600MBs is the normal running amount it uses; i have only seen 1-2Gbs a few times before.
But as far as it using one core of my processor, I have the Core2Duo by the way, is it possible the other core is malfunctioning? Because, like i said in my first and 2nd post, i have been having slowness issues across the machine in all programs, itunes is just something i use a lot.