Homeguru is correct but it depends on how long you intend to live in the home. In your case, particularly since you live in Minnesota as do I, which means I know what your closing costs will be, you'd need the rate to drop a little more to make it worth your while. The closing costs represent a larger percentage of your loan, the smaller it is because many of the costs are fixed. This means you need a greater margin between your current rate & the new rate for it to make sense.
Ultimatley though, one mans pocket change is another mans fortune. In other words, contact a broker to do the math for you and decide from there.
I'd give you my number but quite frankly I am swamped as it is.