Noises during down shift.

I have read some posts about tranny problems lately, whining transmissions etc... So I drive my car today and guess what I hear....whining from somewhere. It happens mainlywhen down shifting into first @ about 25-30 mph. Its hard to describe the sound, like high speed gears I guess...remember those thing you put in your mouth and blew through, which in turn made a whiring/whizing sound...lol So...what does this mean....and is there a way I can do some at home checks???? I would like to add the car and I assume the tranny have about 120K on them.

Thanks in advance....I will keep searching the forums.