I suggest DLD's kegel routine. If you do it every day you will strengthen PC muscle very soon.
100 quick Kegel squeezes
50 of the following:
Squeeze your PC muscle as hard as you can, hold for 5 seconds then slowly release for 2 seconds. When you have finished the 50 your PC muscle will be screaming. This is a good sign. Now to finish the exercise start squeezing and hold for 1 minute, if you get tired squeeze harder until the minute is complete.