The 7805 is getting hot because your supplying current to the servo thru it. Even though the motor is "just turning" it consumes much, much more current than the PIC. When you start "loading" the servo it will draw even more current and will probably overheat the regulator. Basicly you have four options.

1) Mount a heatsink.
2) Reduce the powersupply voltage. That will reduce power dissipation in the regulator.
3) Use a switching type regulator instead of a linear (78xx type)
4) Only run the PIC on the regulated voltage. And the servo on the raw, unregulated voltage.

Number 4 may not be an option depending on your actual supply voltage and max voltage that the servo can take.

/Henrik Olsson.