Heh. I couldn't believe when i actually met someone in real life who was worried about the LHC. I mean, everyone knows people are weirded out about all kinds of stuff on the internet, but for real?
But no, the LHC panic is mostly just silly attention grabbing, the whole idea of it being dangerous is even more stupid than the grey goo idea.
Well, the actual risk is they create a singularity. In other words, a mini black hole.
They wouldn't be able to contain it, unless they collided charged particles (charge is conserved) and used magnets to keep it from falling.
If it did fall, it would be so dense it would pass through matter. Any nucleus that got close enough, however, would fall into the black hole.
You would have to consider it basically in orbit about the earth's center of mass. So it would fall in an ellipse, gaining mass as it sucks in more matter.
Eventually, though, as it gets bigger and bigger, the earth will collapse into it. Shooop! No more earth, just a bunch of xrays.
Personally, I think we should build a REALLY BIG ONE, but on the moon, around the equator of it. If we made a black hole there, the moon would vanish from the night sky, although its mass would still be there, in orbit, so it wouldn't affect our tides.