I feel your pain, Karen. I've battled purple dead nettle, chickweed, and now Queen Anne's lace that my neighbor let go to seed. I've already spent at least 20 hours weeding. Today, the extended-control Round-Up came out. I just don't have another 40 hours to spend weeding by hand, and this stuff is just taking over everywhere. I hate using Round-Up, but this was a desparate measure.
Karen--doesn't the Preen go on top of the mulch? At least that's what I remember.