an update: i took it to the apple store on monday. the guy agreed the sound was abnormal. they replaced the charger input & the logic board. i got it back wednesday night. it was still making the noise, so i backed everything up as i had a bad feeling about it. by the next morning it was totally dead (probably a bad logic board). so i took it back & they had it ready for me this morning, this time replacing the logic board again & the inverter. it was still making the same noise once i got home.
i called them, & explained my situation & the person immediately said "let me get your info to a manager, she will call you back this afternoon." a few hours later, i get a call back from a manager saying that obviously after 3 logic boards not changing anything, it's time to replace the computer (i didn't even ask for that yet, although i was going to). she set me up with an appointment, & now i have a brand new 2.4ghz blackbook
this has a more noticeable normal "computer hum" than my 2.16, but it is NOT high pitched, & it is NOT whiny...just normal computer sounds. i am so happy & the apple store really did everything they could try & fix it.