I suffered with them as a kid. When they removed the first one it just grew back ingrown. Then I went to see a really great chriopodist and he ended up cutting out the sides of the nail and then doing something to the nail bed at the sides (it was a REALLY long time ago so I'm not sure exactly what) and I have never had any problems since.
Don't let them just whip the whole thing off, it's not a cure.
Edit: Also, yes it's sore afterwards. You'll want open toed shoes if possible (not ideal in this weather I know) and just follow the aftercare instructions they give you religiously and keep them clean.