This is pure math. Just sit down and figure out which one makes more sense. Given you don't intend to stay in the house more than 7 years - and certainly no more than 10- it's almost certain the ARM makes more sense.

We are financially stable and can afford the reset of the arm in 7 years (it has a cap). The ARM is nearly a full point lower than the fixed rate. I also don't know that we'll still be in this house in 7 years, land if we are, I'm almost certain we won't be here in 10. However, the fixed is still low and will be lower than the reset of the ARM if it resets to the cap. If I were planning to be here in 30 yrs, I'd go for the fixed, but now I'm leaning toward the ARM. Would welcome any thoughts.