Gen, Snapshot is a pre-emergent, similar to Preen. I've looked into it, but haven't bought it. Some people say it works better, but I think it really depends on the weeds that you have. Preen won't kill all seeds, and there are a lot of different Preen formulas, so you have to read the labels on all of them to see what it kills in relation to what you have. It's confusing!
I'm dreaming of having a nice lawn someday too. I think there is only one real lawn on my road! The rest of us have green stuff, which is mostly weeds! It's very rural here though, and I don't think that anyone actually cares about having a real lawn. Like you, we're afraid to try and kill off anything cause we'd end up with bare soil!
