i like Stang951's idea.
take the inner door panel off (takes 2 minutes if you have done it 50 times like me). you will see the track in the middle. i would steel wool it, then lube it (i use synthetic grease, which is way overkill). take note of the bushings on that rail. there is one on top and one on the bottom. if one or the other is toast (the rubber wears through, to leave metal on metal), then it will screach. also, check the plastic deals on the bottom of each window. if they are not right, and allow the window to ****, the window will fight to go up.
BTW, the bushings (or lack thereof) sound like nails on a chalkboard when down to metal on metal.
good luck.