Well, first off, remember just because it sucks doesn’t mean it will be better somewhere else and with the economy where it is, finding the right job (or any job) might be much more difficult than you think.
With that said, if you can afford it (and think very very carefully about whether or not you really can), quit. I’ve taken to heart some of the best advice was ever been given: if you wake up in the morning and dread going to work, it’s time to go mow the lawn. It’s not always easy, but for me at least, has made me a great deal happier.
Either way, good luck, and let go of some of that stress, it’s not worth holding on to.