as mentioned, you need to consider the time you will live in your home. if you are intending to move in 3-4 years the arm
might be a fine choice. if you are happy where you are and intend to stay put, the longer term fixed rate isn't a bad idea.
the issue with the arm is what if the market turns tomorrow? you need to be thinking about not only this house but your next. if you commit to an arm and then decide to stay for more than 5 years, you are NOT guaranteed that you will be able to get a rate anywhere near today's. if rates really jump or the housing market in your area drops out you might not find as many buyers willing or able to buy at your price.
also, refinancing in an inflated market with an excessively favorable appraisal could really hurt you if the market turns. if you are simply refinancing to get some cash out tax free ok. your prerogative.
if you are refinancing though in a market that is bloated you need to be sure that your appraised value, and therefore loan, will hold reasonably true if the market turns. otherwise you could end up with a loan that is bigger than the house's "true" value. i know, i know... what the market will bear, blah blah blah.
so generally speaking you need to consider whether this is a house you'll likely live in more or less than 5 years. short = arm, with the knowledge that you could get hit if you decide to refinance in 5 but the rates have really jumped. longer term fixed if you intend to stay or the security of a fixed mortgage gives you some peace of mind.
a question for you - where are you located? if you look at the link below it lists cities and the jump in sales over the last year. also a link for the previous year. if you are in a market that had huge jumps in sales prices it might reflect well thought community planning and/or solid economic development coming to fruition. if you live in an area where people are getting a 30% gain for no other reason than the market is hot, again just be sure your appraisal is realistic.
http://money.cnn.com/2006/02/14/real...quarter_sales/
didn't mean to complicate the simple question of arm vs fixed... but when you mentioned the IO option it worried me. they are being exploited in bubble markets and the people misusing them are going to get creamed if the markets turn... not to mention the banks who lended irresponsibly. if you're in an emerging market whose solid gains are backed by economic reason, well good for you. people can make a lot of money being in the right town at the right time.
hmmm. guess i'm done ranting for now.