We get a few ants in our dining room every spring, but I just sprinkle borax around and sweep really well for a few days and they go away.
This year they were really bad, and spread to the carpet. The borax wasn't cutting it. I tried making this homemade ant bait from borax, sugar, and water, and the ants loved it.
I can't honestly tell you whether it was this bait, the commercial ant spray, or Mr. Mordecai caulking the crack outside the house, but we did eventually get rid of the ants.