It depends how much the house is your are gonna buy. Being a first time buyer you should be able to get an FHA loan, there is a cap on how much you can borrow. I think it has been recently raised to about 180K. You should be able to get in a house on a FHA loan with zero down. If you dont have 20% down you will end up with PMI (premium mortgage insurance) will cost you about $100 extra per month but it will be in your payment.

I have had my last 3 house with country wide. Im on a 30 year fixed. Country wide has been easy to work with. If you buy a house at 150k for 15 years it will carry a steep payment. My suggestion is just do a 30 year. Set yourself up on a biweekly payment so you are making the extra monthly payment every year and it knocks off about 6 years on your term. Then pay extra if you happen to have the extra money.