Hi Danielle!
Here's a link about supplements that you may find helpful:
http://www.atkinsdietbulletinboard.c...ad.php?t=53442 (The Beginner's Guide to Nutritional Supplements)
If you've never taken supplements at all before, you may just wish to start off with a good multivitamin so that you get into the habit of taking a supplement. That would be better than to purchase a whole bunch of supplements, only to have them hanging out in your cupboard for years and years.
As far as taking iron, most folks on Atkins don't need to because they consume quite a bit of iron from meat. However, there are those that are still anemic, even with the increase of protein in their diets. Your physican can tell you for certain whether you need to take an iron supplement or not. If you do, taking it with food helps with the nausea, a common side-effect.
Best of luck to you!