Conventional wisdom holds that buying a home is almost always better than renting, because renting is throwing money down the drain. I've heard that, if you're planning to be in the same place for at least three years, it's best to buy.
There are calculators to help put numbers with this:
Suze Orman discusses this in detail at http://biz.yahoo.com/pfg/e10buyrent/. She estimates that additional costs of home ownership add up to about 40-50% of the mortgage payment.
Now, let's assume that you've worked out the numbers, and that you can afford that home, and you know you will pay more on a monthly basis, but you believe that, between growth of principal and appreciation, you're better off. This is often true, housing bubbles aside. What about other negatives of home ownership?
Reduced flexibility in terms of moving. After all that time spent making a house a home, it's going to be much harder to pick up and move. But what if your neighbors are loud, or you have the opportunity of finding a better job in another city?
Being your own handyman. Lots of things need work in houses, from gutters to chimneys to lawn maintenance; while there are service providers to handle all of these needs, the cost of paying someone to handle all these tasks adds up quickly. And even if you're having someone else do it, you'll need to devote a lot of time to phone calls and waiting around for them to show up.
Longer commute? Many people end up buying in more peripheral neighborhoods, which adds time getting back and forth to work. That time might be pleasant, but often it entails sitting in traffic, with the attached expense and frustration, not to mention environmental impact. And, even if your house is close to your current workplace, if you switch jobs in the same city, you're likely to find yourself with a longer commute.
All in all, it's often best to buy, but the conventional wisdom overstates the importance of that choice.