Hi Aaron,
Don't chop! Use zero crossing detection.  Decide to turn On or Off the
lamp, and leave it alone for a half cycle (1/120s).  Chopping it causes
LOTS of grief.  Radiated noise and excessive switching currents, will be
greatly reduced if you switch when the voltage is zero.  Depending on
the inductance of the load, the current might even be near zero.  Also
use opto-isolation to protect the PIC and other circuits.  The PIC
should have time to do a calculation every 1/120S?
Good Luck
Mike