Considering the economy, I'd look at job security as the first priority. Much more than pay or benefits.

Which of the two companies is more likely to weather the coming recession and keep you employeed. Does one company hire and fire based on senority? I'd avoid them if they do.

Otherwise, the American business world today has no ethics and they definately have no loyality, so I wouldn't shed a tear if you decide to leave and go with the new company. That's what they lobby for and that's the way they want it, so that's the way they get it.

However, I would give them notice, if possible, explain the situation and in the end they might offer to match, if you like the new company. Be as gratious as possible. It can't hurt.

I'm sure this happens all the time, when people are applying for multiple jobs and get multiple offers, but not all at the same time. Besides, with the job market going the way it's going, I'm sure they'll find a replacement for you quick enough.