Many mortgages with 5% down do require MI (Mortgage Insurance) but there are a few ways around it. It's true that a couple of months ago loans were being pulled off the market quickly, especially those that had favored buyers with less then 20% down. However, those loans are coming back and by doing an 80/15/5 (First note is 80%, second is 15%, buyer puts down 5%) you can avoid MI altogether. I recently had a buyer qualified by two different lenders doing an 80/20 and no MI. In fact, we are in contract now.
However, if you find for some reason that you don't qualify for those programs, you can sometimes prepay MI and avoid paying it on a monthly bases. I sold a home about 2 months ago and we asked the seller to pay $3000 in buyers prepaids which we used to prepay the MI, saving a few hundred dollars a month for the buyer.
Prepaying the MI isn't always the best deal, however. You can determine which is best, prepaying or paying on a monthly basis, by taking the MI and multiplying it by 24 (2 years) and seeing which is less. I use 2 years because that is the mark that most recently has been used by lenders for removing the MI from the loan. As Ute noted below, the lender will not necessarily remove the MI on their own, you will have to apply for removal and jump through a few hoops to get it done, but it will be well worth it!
Good luck to you, and congratulations.