New 2.4ghz MacBook aluminum owner here. There a very low hum coming from my new MacBook, and it is always there. I don't know if it is the hard drive or the fan, but is is quite obvious in a quiet room. I compared it to my 2003 plastic iBook, and the iBook is SILENT compared to the new MacBook. I checked the iStat Pro stats, and the fan is around 2000rpm and the temps are normal. Anyone else notice this? I love the new machine, but this noise is slightly disappointing, especially compared to a 5-year-old iBook. Thanks!