If Palin wins NH somehow, the race is over before we even get to SC; but I don't think it's likely. Recent polls had her finishing second in NH, though, which would be a nightmare scenario for Romney going into SC.
If Palin wins SC, she will become a 60/40 favorite to beat Mitt. FL will be truly up-for-grabs at that point, and Mitt will have to suffer through huge wins for Palin in TX and most of the South. He'll see some trickle from UT and maybe MI and WI, but a SC win will be a big stepping-stone for Palin. It will be hard for Mitt to overcome.
That being said, Mitt will have two die-hard allies in SC in Lindsey Graham and Jim DeMint, plus he's trying to romance Nikki Haley into at least staying neutral.
I give the nomination odds like this for now:
Mitt: 50% chance,
Palin 40% chance,
Other 10% chance.
You’re leaving Wyoming out of this.
Granted, it’s not a big state, but I’d argue it’s the most conservative state in the nation.
It’s also not one of these balogna open primary states.