Brakes: One Side Working, One Side Not?

[fivespeed3.0]

I've got a 2000 Ranger 4X4 3.0L and I suspect that the passenger side front and rear brakes are working, while the drivers side front and rear don't. The truck pulls to the right when braking, and once when I was pulling out of my garage with snow on the ground, I applied the brakes pretty hard, and looked at the pattern in the snow. There were skid marks in the snow on the passenger side, and none on the driver's side. Could these be symptoms of a bad master cylinder? Any suggestions? I've got ABS, but the ABS light is not coming on.

 

[Ranger44]

My first conclusion might be that the divers side caliper is frozen.