Gray poly pipes sweating vs. leaking?

Ahhh... the joys of homeownership. We knew moving in that this house had the pex/poly pipes, but at least they were the gray ones, not the blue ones. Anyhow, now it looks like either one place or a couple of places they're starting to leak. Fun. Not sure what to do since there's no way that we can afford to replace all the piping in the house. Then again, looking closer, it might be just that they're really sweating with condensation. Not sure how to tell the difference. We're getting a drip or so ever 5 minutes in a couple of different areas.
Any ideas/thoughts?