Everyone's adive here is right on BG...
I've only had one VERY small bout with PM and it was my first grow, in a spare closet, with bagseed and a single 400W HPS batwing....No extraction fan and only 1 oscillting fan blowing in the closet and another small box fan in the closet... About as far from optimal as could possibly be.
However, I used the Organicide, like Rounders suggested already. It does leave a strange fishy smell which i didn't particularly care for, but it sure took out the mildew pretty damn quick. I sprayed my plants 2 days after the application of Organicide with plain water hoping to get any of the oils off my plants to be rid of the fishy smell and didnt want the taste on buds thats for sure. Organicide is really easy to aqquire (Lowes/HD) and also works great on pests, and took out the Mite pretty good on my recent run...
Like others said, remove any of the affected areas of the plant, and dont smoke those buds. The plants can be salvaged so don't start ripping your hair out like I wanted to when I had it.
Also, one more small tip.. Like others said, fix whatever is wrong in your grow space like the others said...perhaps you need better ventillation. But before you start another round of plants, I would wash down EVERY inch of grow space with a light Bleach/water mixture, to kill of any of the mold and mildew spores that may be lingering around.
You will be fine, and the plants will still mature, you may just lose some yeild, but hey its better than loosing your whole plants.
Good luck!