Finally fixed it
Ok, after reading multiple suggestions..this is what I ended up doing.
I took the belt off and went over each metal ribbed pulley (Crank, PS, AC, Alternator) with a 4.5" angle grinder w/a wire wheel attached. My crank pulley was pretty rusty, the power steering pulley was also - others weren't so bad. I spent maybe 10 minutes on each.
To clean up the crank pulley, I ran the truck (w/out the belt), got under it and used the angle grinder, a wire brush, and a screwdriver to clean all the v's in the pulley. This probably wasn't the safest thing to do, but the pulley came out looking like new.
This did not fix the problem with my old belt (from Advance Auto), although it did quiet it down a lot..I still had squeaking off idle. So I picked up the NAPA belt for over twice the price of the Advance belt..but the truck is now silent at all RPM's!
So I guess my suggestion would be - if its squeaking, clean the pulleys as best you can..and buy a GOOD quality serp belt. Thanks everyone for your replies