Several years ago my wife and I were in the same situation. I got a lot of helpful information from the local universities and the Federal Government (yes, even the EPA!). I'm a contractor, so I tend not to believe all that I hear from contractors since they have a vested interest in selling you the service or product they provide, but do talk with as many contractors as possible to find out the range of your options and their respective costs.
We finally decided to cover the old paint with primer and 2 coats of paint after we saw some test data showing how much lead is in the air after the paint is removed. We have not regretted this decision.