I've got tiny ants coming in from the window above the sink in the kitchen. We are taking care to make sure the area is more clean since the ants started coming in. I've tried a few products, and I seem to have the best luck with the Terro liquid poison (I don't remember the exact name at the moment). When they come in, they don't go too far beyond the poison. However, they don't seem to be going away. It seems that I have to keep that stuff out there constantly since they started coming this summer. I feel like I'm just giving them a nice meal. I'm interested in product recommendations, or any other ideas. I'm not afraid to poison the heck out of those suckers!
You have to stop them at the source. Use baits that ants will gather and take back to their nest, or follow the trail back to the nest and Raid the entire trail + nest.
I've also been known to put a pesticide in my lawn and flower beds once or twice a year to keep them from getting near the house. I try to make a 10' perimeter around the home.