We just had a big convo about this on asec as well as on here in the general forums so you must have just missed it..

First off your car is a v6 im taking it, with the 2.5L? It seems to be pretty prominent in these cars that something with a whining noise starts happening..  The whining noise your getting is most likely not your transmission..

When your in park, neutral, or drive, your whining noise is probably there.. If you wanna test to see if its your transmission put it in park, and rev it to about 4-5 grand.. I garuntee you get a pretty high pitched winding sound, its gonna be really loud because first off your cars not that warm yet, and second off your not moving so your not getting the wind in your ear or other traffic..

Id say your getting that noise.. As long as your transmissions not jerking or sluggish or anything, then its usually not a transmission problem. Your fluids probably good, as well as your filter..

We found this problem to be the idler pulley, which is on the passenger side of your car (front of the engine).. Its not that expensive, just goto advance and get a new one..
Your idler pulley's bearing is bad, so its gonna cause some squealing and whining noises. Of course its gonna be most noticable at a higher speed because your at a higher rpm.. Its most noticable over 2,000 it seems..