GARDEN: Ants in Garden - Harmful or not?

We have always had a serious problem with fire ants here, but I can't decide if the ants in the vegetable garden are fire ants or not.  I am trying to figure out whether or not these pests are harmful to the garden.  It seems that where you see ants, there are aphids and that aphids are a much bigger threat.  This is what I have found so far...

ants & ahises image by Marek Kosmal from Fotolia.com

Most ants are harmless and pose no threat to the health of your vegetable garden, typically using it as a path on the way to somewhere else. Some types of ants can actually harm your vegetable plants, however; for these pests there are safe pesticide alternatives to rid your garden of them. Fortunately, many solutions are household items: You may already have the materials necessary to get rid of ants in your vegetable plants.

1. Use cinnamon to rid your garden of ants. Ants do not like cinnamon or cayenne pepper. Ground cinnamon or cayenne pepper can either be sprinkled in a thin line, forming a perimeter "fence" around the particular plant that is being attacked, or sprinkled around the entire vegetable garden. Ants will not cross the spice line.
2. Soapy lemon water will repel ants, but use caution around plant leaves and stems. A simple combination of soap and water can also deter ants and will not harm your vegetable plants or the people eating them. Have a spray bottle ready with soapy water near the site of the ant infestation; you can spray them as you see them. Adding a bit of lemon juice to the mixture is even better for repellent purposes, but be careful spraying anything acidic onto your plants, as it can burn delicate leaves and stems.
3. Ants are attracted to aphid-infested plants.
   
   
   reed aphids image by Adrian Hillman from Fotolia.com 
   Companion planting is a safer way to control pests in your garden. Mint, for instance, is great at repelling insects. If fresh mint isn't available or isn't working well enough, dried and crushed mint leaves can be sprinkled in areas where the ants are infesting. Ants are also sometimes attracted to a vegetable plant because they're eating aphids and aphid byproducts that have also infected the plant. Chives, basil and calendula are good aphid deterrents. If the plant is heavily infested, though, it may be too late to save the plant.
4. A mixture of grits and sugar sprinkled near the ants can elicit positive results. The ants are attracted to sugar, and they will eat the grits more readily when they're sweetened. When the ants hydrate themselves, the grits will expand and kill them.
5. Citrus oil is a safe alternative to ant pesticides or chemical repellants.
   
   citrus image by John Keith from Fotolia.com 
   Ants detest citrus of any kind. Citrus oil is the most concentrated, long-lasting and weatherproof citrus extract you can use. This method works best by dipping a cloth or piece of string into citrus oil and encircling the vegetable plants that are affected by the ants.