OK, how do I minimize or stop that horrible squeak I get from sliding my fingers up and down the strings on the way to the next note or chord? Do I just have to get better and pull off the strings more between changes?
Basically apply less force. You don't need as much pressure to sound a note as you would think.
I'm a musician/composer before I'm a guitar player.


R.I.P Jimmy "The Reverend Tholomew Plague" Sullivan.
New strings will do this until they lose their shine. Once they get worn in it will be less.

Yes, less force is the key but pulling your fingers off before you slide from one chord to the next will definatly eliminate the noise.

Also, try some Fast Fret.
Imagination is more important than knowledge...
It is a miracle that curiosity survives formal education.
- Albert Einstein -
Try Flat-Wound or Ground-Wound string. Ground-Wound will give less noise. Flat-Wound will give even less noise than Ground-Wound.
If the human mind were simple enough to understand, we'd be too simple to understand it.
Heavier strings will make that noise less audible.

Making sure your hands and strings are clean helps.. get a string conditioner from Guitar Center.
When you do the slide, raise your fingers a bit. If you want to completely do away with it, raise your fingers to where they're still on the strings, yet muting them. Make sure you can still access the chord with ease while doing this. Since your trying this, try lightening up on your chording pressure, maybe. You'd be surprised how much easier and relaxed you can play when you do that.