As you research financing the purchase of your first home, you notice that theinterest rate on an adjustable-rate mortgage (ARM) is lower than that on a fixed-rate mortgage. In addition, there would be a payment cap on your monthly payments for an ARM and you would have the option to convert to a fixed-rate mortgage. You are tempted. Interest rates are currently low by historical standards and you are anxious to buy a house and stay in it for the long term.Why might an ARM not be the right mortgage for you?